In most years, seeing that the Boston Red Sox  had the best record in the American League East and the top run differential in baseball at the end of April would come as little surprise. After all, the Red Sox have won two World Series titles in the last decade and annually find themselves in playoff contention.
But 2013 isn’t most years, because rarely are the Red Sox coming off a season in which they lost 93 games and suffered national embarrassment on a regular basis. Most observers expected the Red Sox to rebound somewhat from last year’s debacle — if only because key players would return to health and Bobby Valentine would be anywhere other than Boston — it’s safe to say that few expected the club would be among the class of baseball after the first month.
While the Red Sox have benefited thus far from the improved health of Jacoby Ellsbury  andDustin Pedroia  and the additions of Mike Napoli  and Shane Victorino  on offense, it’s pitching that is truly driving the turnaround. Last year’s collection ended up with the fourth-worst ERA in baseball; through the first month of 2013, they’d allowed the fifth-fewest runs in the game. Even more notable, however, is how they’re getting there, because this crew is striking out hitters at a record pace. After Jon Lester  and Junichi Tazawa  teamed to punch out seven Toronto Blue Jays  to finish off April on Tuesday night, the Boston staff stood at a combined 9.94 strikeouts per nine innings.
That strikeout pace is more than two and a half batters more per game than the 2012 Red Sox had, which would be an enormous increase. Not only that, it would be the highest team rate in baseball history if they were somehow able to maintain it for the entire season. How have they managed to increase their strikeout rate so much?
It’s the pitchers
This may seem obvious — after all, the pitchers are the ones collecting the strikeouts — but there’s a lot more to it than that. The roster turnover during and after the 2012 season rid the Red Sox of several pitch-to-contact types, most notably Aaron Cook , who struck out just 20 batters in 94 innings. That’s not a typo. In fact, only one pitcher in the last 60 years threw as many innings as Cook and struck out fewer. (Here’s your chance to take a bow, Larry Pashnick of the 1982 Detroit Tigers .) The Red Sox also bade farewell to Scott Atchison (6.31 K/9 in 51.1 IP) and Josh Beckett  (6.64 K/9 in 127.1 IP), while banishing Daniel Bard (5.76 K/9 in 59.1 IP) to the minors after a failed attempt to convert him into a starter.
The departed have largely been replaced by newcomers like Ryan Dempster  (12.9 K/9 in 30.0 IP) and Koji Uehara  (10.13 K/9 in 10.2 IP). While Uehara’s performance is largely in line with his career norms, the 36-year-old Dempster has been a revelation, striking out hitters at a pace he’s never come close to before. Dempster has always maintained decent K rates, but pitchers of his age rarely experience and then maintain such an uptick in performance, but at least in this case there’s evidence of improvement to point to rather than simply “it’s just a small sample size.”
Dempster has had an effective splitter for several years, but this year he’s throwing it more than ever, up to 18 percent of the time, while relying less on his fastball. That’s an out pitch when hitters chase it, but it’s also one that rarely ends up in the strike zone, which may also explain why Dempster’s walk rate is higher than it’s been since moving back into the rotation in 2008. As Jeff Sullivan recently went into great detail about at FanGraphs , Dempster has also slightly shifted his position on the rubber and his pitch location over the plate, largely avoiding the inner half entirely. You shouldn’t put money on Dempster retaining a K/9 date north of 12 all season, but there’s reason to believe he can sustain at least some of this improvement.
Nearly as important as the newcomers is the improvement from those who remained, and that starts with Clay Buchholz . The former top prospect struggled badly in 2012, ending the year with a 4.65 FIP and a 6.32 K/9. He has turned that around in a big way in 2013, striking out 47 in his first 44.2 innings while allowing a mere five earned runs. Andrew Bailey , Felix Doubront , and Andrew Miller  have each shown improved strikeout skill as well this year, which in Bailey’s case can be attributed in part to better health.
It’s the catchers and coaches
In addition to the big-name items like Dempster, shortstop Stephen Drew , reliever Joel Hanrahan , Napoli and Victorino, Boston gave a two-year contract to 36-year-old backstopDavid Ross , coming off four seasons backing up Brian McCann  in Atlanta. Ross earned a reputation for being one of the better backup catchers in baseball on the strength of his .816 OPS as a Brave, but his value goes far beyond the offensive stat line.
The science of tracking pitch framing — that is, quantifying the positive or negative effect a catcher can have on having borderline pitches being called strikes based on how he receives the ball — is still in its infancy, yet Ross consistently ranks among the better catchers in the game  in the studies that have been run. Backstop partner Jarrod Saltalamacchia  is considered solid, but Ryan Lavarnway  and Kelly Shoppach  — who started 67 games behind the plate last year but are not with the big-league club this year — each grade out poorly.
That subtle upgrade helps all the pitchers, of course, but Ross may also be responsible for some of Dempster’s success. Catching a bullpen session from his new teammate in spring training, he offered Dempster the advice to try to throw all of his pitches from the same arm slot , minimizing the chance that hitters may be tipped off to what pitch was coming. Dempster acquiesced, and the data bear out the difference; his pitches are coming out far more consistently than they used to, and the veteran pitcher is off to one of the best starts of his career.
Beyond the impact Ross has brought, new manager John Farrell and pitching coach Juan Nieves deserve credit as well. Farrell, a veteran of eight big league seasons on the mound, and Nieves, who pitched for the Milwaukee Brewers  before injuring his arm at 23, have tinkered with the release points of Buchholz, Doubront and prospect Allen Webster . Buchholz and Doubront have each shown improvement so far, and Webster has become one of the more talked-about pitching prospects in the game.
It’s the league
When we noted above that Boston’s 9.94 K/9 through April would be the highest team rate in history if kept up over an entire season, that was true. However, it’s worth pointing out that the second-highest rate ever is this year’s Detroit Tigers, with 9.79, and the eighth-best ever is the current Kansas City Royals  staff at 8.51, so you can probably see where this is going. The top 40 pitching strikeout seasons have all come since the turn of the century, and that’s no surprise, because it’s a well-established fact that today’s hitters whiff far more than their ancestors did. (As Buster Olney noted , the top eight months as far as strikeouts go in the history of baseball are the last eight months of play.)
However, the 2013 American League is taking that to a new high. Last year, all AL pitchers struck out 7.41 batters per nine, which was less than the 7.69 their National League counterparts managed — to be expected, given the weaker lineups NL pitchers face. Yet this year, that number in the AL in April shot up to 7.82, while it actually decreased in the NL to 7.57.
Why? It’s likely oversimplifying to pin the swing on this reason alone, but it’s hard to ignore the one huge difference between 2012 and 2013 in baseball: the dreadful Houston Astros  — on pace to be the most strikeout-prone offense in the history of the game  with a whopping 26.3 percent strikeout rate through April — shifted leagues to the AL. The Red Sox had the benefit of playing Houston for a four-game set in Boston in late April; they stuck out 41 Astros during the series.
The Red Sox probably aren’t going to end the season as the all-time strikeout leaders, because it’s hard to see pitchers like Dempster maintaining quite that level of performance, and we’re of course dealing with small sample sizes for every pitcher discussed. Still, there’s a lot to like about this staff. Last season’s disaster was less about the narrative of “fried chicken and beer” than it was about poor health and indifferent coaching, and the 2013 Red Sox seem better situated to succeed than last year’s version in every regard.