As the Reds call up Nick Senzel, a look at Rookie Seasons and Expectations

Happy Nick Senzel Day, everyone!

Yes, the time is finally upon us. Almost 35 months ago on the dot, the Reds used their second overall pick to draft a third baseman out of the University of Tennessee, a player who many analysts projected had the most polished and MLB-ready bat in the draft class.

Even though it was not even three years ago, Senzel’s path from college to the majors has felt longer and more turbulent than it perhaps actually was in retrospect.

First were the position changes: Senzel was drafted six months after the Reds traded their All-Star third baseman to the Chicago White Sox, but the next year Eugenio Suarez played himself into a seven year contract and cemented his role in the hot corner. Senzel played some second base the next year, but the emergence of Scooter Gennett as a breakout All-Star blocked that position as well. There was talk of Nick Senzel at shortstop for a while, but the team didn’t seem impressed by his defense. Finally, Billy Hamilton’s departure this offseason created Senzel’s fourth potential landing spot, one which finally seems to be an effective combination of defensive capability and positional need.

There were also the injuries, with Senzel losing time in 2017 and 2018 to vertigo, followed by a fluke hand injury that ended his 2018 campaign in June, and then a sprained ankle in the twilight hours of spring training, from which he only returned last week.

Despite the mayhem, Senzel’s stock as an elite hitting prospect has risen. Before the 2017 season, Senzel was rated the 26th best prospect in baseball by MLB Pipeline, and his spot jumped to #7 and #6 before the 2018 and 19 seasons, respectively. With so much confusion and uncertainty surrounding his future, it would be understandable for Senzel’s production to falter, but instead, he has been the beacon of consistency throughout his time in the minors.

It’s easy to see what so many scouts across the league like about Senzel, he doesn’t appear to have an obvious weakness at any part of his game. With a consistently above average walk rate (reliably hovering around 10%) and a below average strikeout rate (reliably hovering around 20%), hitting .300 or better in nearly every stop in the minors and an overall hitting approach that’s 50-80% better than his league, Senzel seems to effortlessly find success everywhere he goes. There’s nothing left for him to do but bring that success to the majors, where he’ll debut in his age 24 season as only the fourth player in the first round of his draft class to reach the bigs. (LHP Eric Launer with the Padres, RHP Dakota Hudson with the Cardinals, and SS Carter Kieboom with the Nationals).

So with such an elite pedigree given to his skills and so much hype behind his debut, what can we actually expect to see from Nick Senzel, going forward?

It’s hard to project minor leaguers as they enter the big leagues – not only is the data available from the minors much less complete, but the same skills that bring success in the International League do not necessarily translate to the style of play in the National League. Amateur and professional scouts throughout the game have built entire careers on trying to make these predictions, and some random fan on the internet will not have more insight in this area than such an expert in that field. But, there is some common wisdom and some past examples we can look to as us fans calibrate our expectations for the newest Cincinnati Red.

One piece of commonly held knowledge is that plate discipline tends to be the biggest indicator of success in the majors for future prospects. The reasoning behind this is that it’s a highly transferable skill – a player may mash AA fastballs over the fence all day of the week, but finds he struggles mightily to catch up to the faster and livelier heat in the majors; while a player who is incredibly adept at discerning balls and strikes and selecting his pitches will probably be able to carry that skill into the big leagues. And of course, there is the obvious factor that a player who can walk frequently and swing at only the best pitches will likely find more success with the rest of his approach. The example Reds fans are all too familiar with is the Joey Votto / Jay Bruce comparison:

This of course isn’t a hard-and-fast rule, many players with low walk rates and high strikeout rates can find success in the minors and majors. But as far as indicators goes, it is one of the better ones we’ve found. In this regard, Nick Senzel is certainly above average, if unspectacular. His 9.8% walk rate in Louisville in 2018 beat the 8.3% International League average by a modest amount, and his 11.1% rate in Pensacola in 2017 was a similar margin higher than the Southern League’s 9.1% average. The 21.7% average strikeout rate in the 2017 Southern League and 21.9% rate in the 2018 International League were both higher than Senzel’s rates, but again, by only a modest margin. While it doesn’t jump off the page, Senzel’s ability to beat the average with such immutable consistency is certainly an encouraging factor going forward.

Senzel also has many other aspects to his game that he should hopefully be able to carry over. While his hit tool is doubtless his most impressive aspect (Fangraphs rates it as a future 70 value on the 20-80 scale), all other tools rate above average, and he has shown throughout his adventures in different positions to be a consistently plus defender. His glovework is deliberate and his speed gives him decent range at most positions. He has also averaged 27 stolen bases per 162 games in the minors, and is likely to bring above average baserunning with him to Cincinnati as well.

All this talk of his tools and skills still feels kind of like guesswork, though, doesn’t it? Because data is fun baseball has a lot of it, let’s use some data on recent rookie seasons in major league baseball to form an idea of what qualifies as a spectacular or disappointing first outing for new players.

In 2018, there were 26 position players throughout baseball in their rookie season with at least 300 plate appearances. Our own Jesse Winker was one of them. Of the 26, 5 had below replacement level WAR, 13 had between 0 and 2 WAR, and 6 had above 3 WAR. The top of the list has some familiar names, and some perhaps more obscure ones: Joey Wendle of the Rays tops the chart with 3.7 WAR, tied with Braves phenom Ronald Acuna Jr. The average wRC+ of the group was 104 with a standard deviation of 23.8, meaning 68% of players fell between 80 and 128 wRC+.

That’s a pretty wide range, don’t you think? Looking at just one year feels a bit small. Let’s expand the list to the 213 rookie seasons for position players in baseball from 2010 to 2018 with at least 300 plate appearances. That will give us a much wider sample.

Here we get a distribution that feels much closer to our expectations. Mike Trout of course sticks out like a sore thumb, his remarkable 167 wRC+, 10.1 WAR season head and shoulders above anyone else in the group. He has a couple of close companions: Aaron Judge and Jose Abreu’s monster rookie campaigns, and Corey Seager and Kris Bryant’s memorable rookie of the year campaigns in 2016 and 2015 are outliers. Beyond those, we see that rookie seasons fairly closely resemble the distribution we’d expect in the general population of major leaguers: the vast majority are above replacement level but worth less than 2 wins, with wRC+ crowded around the 100 league average.

Truly spectacular rookie years are exceedingly rare: while 33 of 140 qualified major league hitters notched over 4 WAR last year (23.5%), only 14 of 213 rookies over 9 years passed 4 WAR (6.5%). Part of this can be attributed to playing time. Rookies tend to get fewer appearances than established major leaguers, many times finding themselves part of a platoon or getting mid-season call-ups, which can reduce their total season WAR totals. Another aspect is selection bias, since established major leaguers are more likely to produce at the highest level than rookies, who to this point are largely unknowns.

While we’re talking about selection bias, isn’t it unfair to count all rookies in our selection? I mean, that includes every Joe Schmoe who managed to make the roster that year. We’re talking about Nick Senzel, an annual Top-10 Prospect with an elite minor league history behind him. Why not look at other top 10’s performances?

Using Baseball Prospectus’ list, one can compile a list of the top 10 hitting prospects each year from 2010 to 2018. Here’s that list:

Looking at this list should give you some cautious optimism about the odds of success for our favorite prospect. There’s a lot of spectacular names on there – beyond the obvious angelic fish man, Carlos Correa, Nolan Arenado, Corey Seager, Kris Bryant, Buster Posey, George Springer, Francisco Lindor, Freddie Freeman, Manny Machado, and many others find themselves on that list. But it doesn’t exactly read like a who’s who of future All-Stars; also on the list are names like Lewis Brinson, Domonic Brown, Blake Swihart…Billy Hamilton? How about that.

Obviously not every top prospect pans out, but looking at the list of the past decade’s top 10’s certainly instills hope, as the wash rate for these players is much lower than the general population of rookies as a whole. There are 50 unique names on that list that have had what would qualify as a rookie season in the majors so far. Of those 50 names, 29 had a wRC+ north of 100 in their rookie campaign, and 19 north of 120. Only 7 notched a negative WAR in their freshman outing, less than the 17 that bettered 2.5.

But, funny story about some of the players that fall in those categories…while Lewis Brinson had the worst rookie season at -1 WAR, the second worst rookie year was held by Javier Baez at -0.8. You know, the guy that came in second in MVP voting last year? His 54 wRC+ was the worst on the list, but 8th from the bottom was Nolan Arenado at 77 wRC+. Nolan Arenado! Wil Meyers notched a 129 wRC+ in his first season, beating out Bryce Harper, Freddie Freeman, Giancarlo Stanton, and Manny Machado.

That brings us to the last big point I want to make about rookie seasons as we prepare for Nick Senzel. That being, whatever happens in his first month, two months, five months, or even year of his career is not necessarily indicative of how good of a player he’s going to be. It is crucially important to stay the course and not allow small samples to dictate our attitudes towards Senzel.

Here’s a fun experiment: let’s go back to those 213 rookie seasons of the past decade with at least 300 PA’s. Let’s then compare those seasons to the rest of those player’s careers, to see how strong a correlation there is between the two.

I promise this article doesn’t exist just to talk about how good Mike Trout is. What you can take from this graph is that the likelihood of any rookie having an MVP caliber season is incredibly slim, but that doesn’t dampen their odds of a successful career going forward. Matt Duffy had a better freshman year than Buster Posey, and Freddie Freeman notched less than a win in his rookie year. Overall, the R2 value of the graph – indicating how correlated the x-and-y variables are, with 0 being not at all and 1 being perfectly correlated – is 0.315, relatively low. A player may have a good or bad rookie outing, but the data tends to show that it is not as great an indicator of future success as you might think.

Its surprising when you go down the list of rookie seasons to see how many players were given consistent playing time from the word go, and how many weren’t, and how that correlates to their overall career success. It’s kind of a chicken-and-egg question, of course; do players get shuttled back and forth to AAA because they’re not quite good? Or are they not quite good because they keep getting shuttled back to AAA? I’m sure there’s an aspect of both, but it’s easy to see the effect that a tenuous grasp on playing time has on a player’s mentality. A player who doesn’t know if he’s still going to be here next week will press, constantly trying to prove he belongs on the team and try to do too much in every at-bat. When a player gets consistent at-bats – and has it made clear to him that he’s not fighting for his job – it allows the player to relax, to make adjustments, and to grow. Imagine what would have happened to Jesse Winker and Luis Castillo if the Reds had decided that their miserable April 2018’s had justified a trip to Louisville, rather than them working their craft without fear of losing their jobs.

To conclude, I’m incredibly excited for the coming of Nick Senzel. I don’t think a top prospect’s arrival in Cincinnati has been more anticipated since Jay Bruce over a decade ago, and he’ll find himself ready to help the team right away in an area where he’s needed. But I think it’s important to remember how prospect development goes, and to keep in mind that Senzel is unlikely to get any MVP votes this season, or anything close. Senzel is 24 years old this year, and has yet to see a major league pitch in his life. A fantastic year for him does not make him a perennial All-Star any more than a bad year makes him a washout. Be excited, but be patient, and always root for walks.