Zack Cozart has two full major league seasons of playing time almost exactly. In those two season, he has accumulated 4.8. bWAR and 5.2 fWAR. Those are good marks and point out a player who many of us know has been broadly under appreciated. Miscast during the last two years of Dusty Baker’s tenure as a top-of-the-order table setter, Cozart is likely to finally find his proper home at the bottom of the order this year, where his inconstant (but not valueless) offensive talents can be more easily hidden while his defensive prowess continues to shine.

While it is certainly nice to see a player finally put into the correct role, it is important to look into the future, especially now that we have a fair bit of data, and see what we might expect from Cozart going forward.

I made mention of Jay Bruce’s relative youth in my last piece and I need to contrast that with Cozart’s relatively advanced age here. Yes, Cozart will only be 28 years old this year and that means we should not expect a sudden, precipitous decline. However, nether should we necessarily expect him to maintain his recent value. By both WAR measures, Cozart has derived more than half of his value from defense (I expect this surprises no one). Despite previous optimism on my part, I think it’s reasonable to say that he is what he is with the bat: a serviceable, bottom-of-the-order hitter. He’s not going to kill you, but you don’t want him up with the game on the line if you can help it.

What’s important about the defensive portion of his value is that aging curves generally agree that shortstops begin their defensive declines at age 28. The decline during the age-28 season is very slight, but it’s there and it doesn’t stay slight. The point it that while Cozart has been a solid 2.5 WAR shortstop on average, that is as good as we should ever expect him to be. Average is 2.0 and when you start at 2.5, you don’t have far to fall to become below average.

Let’s look at a possible aging curve that takes us through the end of Cozart’s arbitration years.

Year WAR
2012 2.5
2013 1.9
2014 2.5
2015 2.25
2016 2.0
2017 1.5

That’s a pretty gentle aging curve that takes us through Cozart’s age-31 season. You could very easily lop 0.25 WAR of the top of each season starting next year.

The point is this. At best, we can expect Cozart to be average for 2 or 3 more years and then he should be expected to drag the team down. This is what happens with late bloomers. They feel young because they haven’t been in the majors long, but father time gains even when one isn’t in the show. In all likelihood, this is the year Cozart is caught. We might not quite see it, but it’s going to happen. And, sadly, it means that Reds need to start thinking about who their next shortstop is going to be, because Cozart is unlikely to be worth hanging on to until free agency.

I like Zack Cozart, but he is not an elite player, and if the Reds want to continue to be a winning organization, this needs to be acknowledged.