We are referring to the fact that the Boston hurlers are on a spree of hitting opposing batters with pitches that has them on a record-setting pace.
[UPDATE 6/11: Adding Josh Beckett's 3 plunks against the Yankees last night, the Sox have 40 HBP in 62 games, putting them on pace now to plunk 104 hitters in 2011]. This would set--in fact, shatter--a modern record. (The all-time record is 109, but this dubious mark was achieved by baseball's most dubious team, the 1899 Cleveland Spiders.)
And the Sox have Alfredo Aceves, who might see more time in the rotation. Aceves' lifetime HBP rate is .60 per nine innings. He's already plunked 5 batters this season in 37 IP.
Hit batsmen don't even out over the course of a few years; they don't appear to be random. Since Terry Francona has taken over as the Red Sox skipper, his squads have hit 612 batters [EDIT: 616 when we count Beckett's "hat trick" last night].
That gives them a lead of just under 50 HBPs over the second place team (the Texas Rangers, with 567).
As the our "HBP heat chart" (below) shows, while the numbers fluctuate from year to year--and the average number of plunks per team has fallen off by nearly 20% from 2003 through 2010--some teams just seem to have a knack for coming inside, while other teams simply put up HBP numbers that are nearly half of what the Red Sox have been "achieving" (case in point: the Atlanta Braves, who've hit only 358 batters over the past 8.4 seasons.
As you might suspect, the Sox pitchers have hit Yankee batters more than anyone else over this time span. A total of 98 Yankee batters have been plunked by Sox pitchers. The Yankees have hit 79 Red Sox hitters over that same time span.
Right now the Tampa Bay Rays hold the modern record for pitcher HBPs, with 95. (That's back in 2003, when they were still the "Devil" Rays.) The Sox are no lock for a new record, but they are clearly off to a "promising" start. It's rare for a post-season team to lead the league in HBPs, but the Sox led the league in 2004 in HBPs. (The Yankees and Phillies each led their respective leagues in 2009, and they met in the World Series.)
Maybe it pays to plunk...