By and large, the 2013 Boston Red Sox have resembled the all-around juggernauts many fans expected in recent seasons. They have carried an elite offense all season, one with power, speed and on-base skills. Though the starting pitchers have experienced occasional shakiness, the trade for Jake Peavy has provided critical depth and stability.
If there is one area detractors repeatedly probe at, it is the team's bullpen. With multiple season-ending injuries and bouts of late-inning turbulence, those doubts may seem somewhat justified. And yet, that allegedly serious defect has not prevented the Sox from rolling to the best record in the American League.
It should be noted that the bullpen is the unit with the least overall impact on a game, compared to the offense, defense and starting pitcher. But because the tiny sample of innings comes at the end of a game, when the black-and-white result of a win or loss is at stake, its significance tends to get overblown.
That is not to belittle the bullpen, and certainly peace of mind with a lead late in the game is a wonderful asset to have. But truthfully, while the Red Sox do not have an elite bullpen, several factors indicate they have at least an average one.
Solid and Sustainable Peripherals
Saying the Red Sox are a top-10 bullpen by WAR is nice, but that does not necessarily indicate anything going forward. After all, the question is whether or not the pen can sustain its performance the entire season.
But when digging through the peripherals, it is hard to poke many holes. The Sox have not raised any red flags that scream luck, as their 11.3 percent HR/FB rate and .311 BABIP, two traditionally fluky stats, are actually among the unluckiest in the league. Moreover, the team's 2.71 K/BB ratio is ninth in the league. Consequently, the bullpen's FIP and xFIP are virtually identical to its ERA.
What those stats indicate is that the Red Sox will pound the strike zone and thus give up some solid contact in addition to the strikeouts. Indeed, Boston's relievers have allowed a 21.8 line-drive percentage, seventh-highest in the league. So does that mean Sox fans should be worried about opposing hitters getting good contact?
Well, not necessarily. At first glance, it's probably not a good sign that the Red Sox give up a lot of fly balls and do not induce a ton of ground balls. However, looking at the relationship between fly-ball percentage leaders and overall bullpen leaders, there does not seem to be much correlation:
The R-squared value on the chart indicates how strong the relationship is, with one being a perfect match and zero being an exact opposite match. As you can see, 0.00072 indicates an extremely weak relationship.
OK, but you're probably thinking that HR/FB percentage is more important. After all, those fly balls don't necessarily mean anything if they fall harmlessly into an outfielder's glove. Well, yes, that's true, there is significantly more correlation between how many home runs you give up and how well your bullpen fares:
In this case, the R-squared value would want to be closer to zero, since a higher HR/FB ranking means more home runs. So a value of 0.25 is a pretty strong indication that the more home runs a bullpen gives up, the worse off it is.
That's not exactly rocket science, but HR/FB ratio is one of the most luck-based stats and has been shown to vary significantly. So the fact that the Red Sox are in the top 10 of that stat means there is a good chance for some positive regression. Moreover, they've been giving up fewer fly balls in the second half, so they stand to see improvement in that area soon.
Giving up fly balls can be a bit hazardous in Fenway, but the Red Sox are not keeping up some unsustainable home run rate or getting extremely lucky on balls in play. So if the skills are indeed present, then it's time to move on to the next question: Can the arms physically hold up?
No one really knows the answer to that, of course, as injuries can strike at any moment. But the Red Sox have emphasized building depth internally to ensure they are prepared.
With Matt Thornton on the disabled list with an oblique injury, the Sox have five relievers on the active roster who pitched in their minor league system at some point this season. That the bullpen has continued humming alone is a testament to Boston's discipline in building up viable long-term pitching depth.
Arguably the biggest revelation has been Drake Britton, the 24-year-old lefty. After he nearly derailed his own career with charges stemming from a DUI, Britton has straightened out his life and fulfilled his high-level prospect status.
Since his first appearance three weeks ago, Britton has carried a 0.79 ERA, contributing the third-highest WAR among Sox relievers and pitching the fourth-most innings. In that time, Britton has not allowed a single inherited runner to score, and he has gone multiple innings in three of his last four outings.
Additionally, Brandon Workman has stepped up to provide reliable long relief. Setting aside his last rough outing against the Astros, Workman had three consecutive starts in which he went at least six innings and gave up no more than two earned runs. His move to the bullpen was the most significant side effect of the Jake Peavy trade, providing urgent depth behind the Sox's late-inning relievers.
The insertion of Britton and Workman has coincided with drastic improvement in the Sox bullpen. After treading water for the first two months, the Sox pen bottomed out in June then shot back up to the top in July:
For any team, the most dangerous time is the fifth and sixth innings, when the starter is either worn down or the fringe members of the bullpen most hold serve. Despite their youth, the Red Sox's options in those innings look significantly more solid than many anticipated.
Assuming the middle innings do not become a huge issue for the Red Sox, the bullpen looks to have things locked down from the seventh inning on. The trio of Craig Breslow, Junichi Tazawa and Koji Uehara has been money for nearly the entire season. Their performance has been absolutely critical with the losses of the two co-closers at the beginning of the season, Joel Hanrahan and Andrew Bailey.
Of the three, there exists a perception that Tazawa's performance has declined. There is undoubtedly concern that he has already thrown 52 innings, his most since Double-A in 2009. And at times, his gopheritis seemed to indicate he was breaking down.
But recently, Tazawa has turned things around. He has not allowed a run in his last 5.2 innings, and opponents are hitting just .189 off Tazawa since the All-Star break. Moreover, he has been inducing more ground balls and allowing fewer fly balls, a good sign for his home run troubles:
Meanwhile, Breslow might be one of the more underrated arms on the team. Working at times as the only lefty, he's been the team's third-most valuable reliever while also pitching the third-most innings, even while missing all of April with a shoulder injury. And in spite of his low strikeout total, he consistently creates poor contact, with a 43.8 percent ground-ball rate that well exceeds his 37.9 percent career mark.
Of course, the most heralded and valuable reliever has been the Sox's third closer, Uehara. The 38-year-old is going to shatter his career innings high, but he continues chugging along. Hammering home the truism that saves are overrated, Uehara has been the second-most valuable reliever in all of baseball this season, despite just 11 saves.
Over the last two months, Uehara has been quite literally unhittable. He has not given up a run since June 30, 16 outings ago, and opponents are batting a paltry .152 off him this season. And as the wonderful website BrooksBaseball.net illustrates, hitters have been whiffing at virtually everything Uehara throws:
The innings spike may render Uehara useless next season, if his arm does not fall off before then. But at least for the rest of 2013, it seems Red Sox fans can rest easy with a lead in the ninth.
The Red Sox probably do not have an elite bullpen, but that has never been an indispensable ingredient of a World Series champion. The 2011 Cardinals finished 26th in bullpen WAR, while last season's Giants replicated the feat with the same ranking.
Obviously, having a great bullpen never hurts, and some of the young Sox arms will have to move to the bullpen to provide long-term solutions there (looking at you, Rubby De La Rosa). But the Sox pen is certainly not nearly as bad as the two previous champions' and indeed seems like it may become a net positive.
Ultimately, the Red Sox are as complete a team, one through 25, as any in baseball. The bullpen has been the least consistent part of that equation, but it is rounding into shape with about seven weeks of the season left.
As the 2011 Sox learned the hard way, it is most important to peak in September. The bullpen looks like it's headed in that direction and will thus be much more of an asset than a liability.
Unless otherwise noted, all advanced stats courtesy of Fangraphs.com.