Think back to the end of last year's regular season, when there was plenty of concern over the back of the bullpen. Yeah, the Red Sox could always rely on Koji Uehara, but Craig Breslow hadn't solidified his consistencies in everyone's minds, and there was a "Junichi Tazawa" problem the team had to worry about. While that issue was almost certainly overblown, there are real concerns surrounding Tazawa coming into 2014, and his role this year will be determined by how he deals with it.
While he's been an outstanding reliever since shifting to the role full-time, he has struggled in allowing hard contact, a problem that reared its ugly head more than a few times in the second half of last season. If he's able to control this issue, he's more than capable of becoming the second man on the depth chart behind Koji. If not, he could theoretically fall all the way down as far as fifth, behind Breslow, Edward Mujica and Andrew Miller. It's one of the bigger concerns facing any Red Sox pitcher this season.
While Tazawa will always be great at inducing strikeouts and limiting walks, he was far too prone to power at some points last season. Over the year, he allowed opposing batters to hit .265/.294/.447. The last component of the slash line is our concern, as that .182 Isolated Power basically means batters were mashing like Josh Hamilton and Dan Uggla off the right hander last season. That kind of hard contact isn't exactly new for Tazawa, either, as he's given up hits at a higher-than-average rate for his entire career. The .321 batting average on balls in play he allowed last yearwasn't totally out of the ordinary, as that rate is at an alarming .331 mark for his career. The reason for this? Line drives. While batted ball data isn't perfect, it jives with what our eyes tell us in this case. Per Fangraphs, 27 percent of the balls in play Tazawa allowed were counted as line drives, a rate six points higher than the league-average. In fact, only five pitchers with at least 40 innings allowed line drives more often last season, and only six with at least 80 innings over the past two seasons had a higher LD%. It's an alarming trend that Tazawa must work on heading into next season.
As I mentioned above, the 27-year-old is where he is because of his K/BB abilities. While he's not exactly at Koji-ian levels, he's still walked less than five percent of the batters he has faced in each of the last two seasons while striking out at least a quarter of them. It's an impressive feat that would likely make him a much more valuable and well-known if it weren't for his consistent hard contact problems. Look at his career season in 2012, when he sat at a .300 BABIP and a 24 percent line drive-rate, and finished with an ERA of 1.43 paired with a 1.82 FIP. Unfortunately, his ability to stay in the zone is also what hurts him.
At this point, batters know what to expect when they see Tazawa. He's going to throw them a first-pitch strike (he's always done so at a rate well above league-average), and he's going to stay in the zone. He doesn't want to give up free passes. Major league batters are going to adjust to these kind of tendencies, and they've done so after his amazing 2012.
Chart courtesy of Brooks Baseball
The chart above shows exactly where Tazwa threw his pitches in 2013, and it's pretty simple to see the problem there. Way too many of his pitches found themselves right in the middle of the zone, where even the worst hitters have a good chance of putting the barrel on the ball. Ideally, he could find himself on those outer portions of the strike zone. Doing that might result in a few more walks over the course of a season, but I'm pretty confident in saying the team would sacrifice a few free passes in exchange for less extra base hits.
Junichi Tazawa has shown an elite ability with the strike zone, forming an amazing K/BB trifecta with Uehara and Mujica. However, he's also had some major problems with hard contact over the past few years, and it's something that came up at some bad times in 2013. If he wants to be one of the high-leverage relievers in Boston this year, it's something he'll have to get under control. It's very possible an adjustment would result in slightly higher walk rate, but that's a cost that would definitely be worth it. For Tazawa, the difference between figuring this problem and having it stick around could mean the difference between being the eighth inning man and being one of the handful of sixth inning men.