When I was younger, U2, one of my favorite bands, announced they would release a record later that year. I spent hours online looking for live versions of the new songs and leaked material that might give me a glimpse of the new music. The music I was able to access was perfect. I expected the rest of the record to sound the same. I prepared myself for a record that would connect with me in that way that only the most soul-reaching music can.

U2 finally released How to Dismantle an Atomic Bomb, and it was solid. Yet, I was disappointed. It had many impressive tracks but was deficient in areas I couldn’t ignore. Since my initial disappointment, I’ve come to appreciate the excellent elements of the record in spite of its shortcomings. My expectations had set a standard the record would have a difficult time achieving. Getting past those expectations has allowed me to appreciate the record for what it is instead of what I expected it to be.

Many fans have felt the same way about Jay Bruce since he began playing regularly with the Reds in 2008. Bruce was the promise of the perfect record. He was the number one prospect in all of baseball in 2007. He dominated the minor leagues. Many fans and experts expected a Mike Trout type explosion from Bruce early in his career.

Unfortunately, Bruce hasn’t played up to such billing. Between the majestic homeruns and defensive gems, Bruce has experienced deep slumps that often last several weeks. At times, Bruce has carried the Reds offensively. Other times, he transforms into a black hole that frustrates fans and out spoken announcers alike. He hasn’t lived up to the promise of baseball’s number one prospect.

But from 2010-2013, Bruce was one of the best right fielders in baseball. He averaged 120 wRC+, hit 121 homeruns, and compiled 14.1 WAR. He had the second most RBIs among right fielders in that stretch with 375. Bruce also won the Silver Slugger award in both 2012 and 2013, ahead of Jason Heyward, Justin Upton, and Giancarlo Stanton.

As Bruce entered his age-27 season in 2014, we could have easily made the case that he would take the next step into superstardom. He had just come off a 4.0 fWAR season in which he tied his career high for extra base hits. He had strong defensive numbers. One former GM and leather pants enthusiast predicted Bruce would win the MVP award after seeing him in Spring Training. But as we all know, the breakout season never occurred. Bruce struggled early, got hurt, and from July through September, played the worst baseball of his career.

Bruce wasn’t just bad. He was one of the worst players in baseball. Along with only 62 games from an ailing Votto, Bruce’s disaster year sunk the Reds’ offense. For better or worse, the Reds now have a left fielder, but without a return to form from Bruce, the Reds likely remain a below average offensive team.

And thus we hope that Bruce’s struggles can be attributed to an unhealthy knee. We take comfort in the thought that the knee caused mechanical problems that left him disadvantaged in an age where pitchers already have the advantage.

The biggest counter to the knee narrative is Bruce’s .300/.351/.540 June. How could Bruce hit so well for one month after returning to the lineup and then struggle so mightily the rest of the year if the knee caused his struggles?

Players with meniscus tears often perform erratically and struggle to pivot properly during their swing. A hitter unable to pivot and generate power will undoubtedly see a drop in their ability to drive the baseball. A player will experience up and downs as their knee continues to recover with some players experiencing long-term consequences from the injury and a lack of strength. Bruce’s numbers seem to correlate well with the effects of a meniscus tear.

In 2014, Bruce hit a much higher percentage of ground balls and a smaller percentage of fly balls than he has since 2010.

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While ground balls produce more hits than fly balls, fly balls do more damage because they are more likely to go for extra base hits. Bruce has derived much of his value from making hard contact. In 2014, he hit home runs at a similar rate to his career average of 17%; he just didn’t hit as many fly balls. Bruce put the ball on the ground at a much higher rate than normal, reducing his power output and adding to his vulnerability to defensive shifts. Bruce rarely hits the ball on the ground the other way meaning that defensive shifts take many of his groundball base hits away.

The drastic rise in GB% might point to a change in mechanics related to the knee injury last season. The idea that Bruce would change from a fly ball hitter to a groundball hitter this quickly doesn’t make much sense, especially at a peak age. The change is more likely related to something physical as opposed to a drop in skill level.

Bruce’s plate discipline also changed in 2014. The table below shows some advanced plate discipline numbers for Bruce from 2010-2014. As a quick point of reference, “O” refers to pitches outside of the strike zone and “Z” represents pitches inside the strike zone. Thus, O-Swing% represents what percentage of pitches outside the strike zone that Bruce swings at during a given season. Check out the Fangraphs Glossary for more information on these statistics, including rough leagues averages for each.

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First, note that Bruce saw the second smallest percentage of strikes in the major leagues among qualified players (38.8%). Even so, Bruce swung at fewer strikes than he had in past years, limiting his opportunities to cause damage with the bat.

Bruce also swung at a higher percentage of pitches outside the strike zone than he had in any other season. His aggressiveness outside the strike zone and relative passiveness inside the strike zone produced not only the highest strikeout rate of Bruce’s career (27.3%), but also weak contact when he did hit the ball.

Bruce displayed great plate discipline before the injury. In April, he had a 17.1% walk rate. As he struggled after his injury, Bruce admitted to trying almost anything to get himself on track. One such adjustment directly led to his five strikeout game against the Cubs in August. Bruce’s constant tinkering seems to have affected his plate discipline in a negative way. He swung at only 25% of pitches outside the zone before the injury before ending with a 33% O-Swing% at the end of the year.

Both Walt Jocketty and Bryan Price have noted that Bruce struggled with weakness in his knee as opposed to pain. Bruce finally began therapy in October and suggests the knee needed rest to fully recover. Healthy knees don’t need therapy in the off season. I admit to being an optimist, but we have some evidence to suggest that the injury and lack of rehab caused Bruce’s knee to wear down throughout the season.

Bruce may be more How to Dismantle an Atomic Bomb than the Joshua Tree, but that’s okay. For 2015, the Reds don’t need Bruce to be more than what he has been in the past. For Bruce to return to his All Star form with the bat, he must make hard contact in the air and reduce his strike out rate by swinging at fewer pitches outside the zone. The injury to Bruce’s knee likely had an effect last season as his batted ball data changed drastically and unexpectedly in accord with what we know about meniscus tears. If he is completely healthy, the Reds should expect a significant upgrade in right field this season. And hopefully one day, Bruce will make that perfect record that we all expected him to make.