Red Sox bullpen, best in baseball?

The Red Sox finished last season with a bullpen ERA of 3.80, second-best in the American League behind the Oakland Athletics' 3.54 and well below the American League average of 4.17. The same group returns intact this season and will be expected to put up similar numbers.

It's fair to wonder, though, if it will.

The Red Sox bullpen looked like one of the best in baseball last season mostly because its pitchers stranded 71 percent of inherited runners last season, second-best in the American League. Only the Yankees (73 percent) were better. The American League average was 66 percent.

That number might not be sustainable. While the American League average has held steady around 66 percent over the last few seasons, the Red Sox strand percentage has bounced around quite a bit:

2009: 71 percent
2008: 68 percent
2007: 77 percent
2006: 62 percent
2005: 61 percent
2004: 66 percent

The smart money has the Red Sox bullpen's strand rate regressing to the mean this season.

"When we had guys on base and guys in scoring position, we actually pitched really well last year," Red Sox general manager Theo Epstein told WEEI this morning. "That’s the type of thing that you can’t really count on year after year."

This is where Epstein's idea of "clutch pitching" comes into play. Stranding inherited runners often can be a byproduct of luck -- or, as Epstein made clear earlier this offseason, lousy defense. One reason Epstein made it a point to upgrade his defense was the fact that he couldn't realistically expect his relivers to pitch as "clutch" as they had last season.

ERA can be a bad way to evaluate relief pitchers because so many outside factors contribute. If a reliever enters a game with a runner on second and promptly gives up an RBI single, that run isn't charged to his record. If a reliever leaves a game with the bases loaded but the next pitcher strikes out the side, no runs are charged to his record.

As elite as the Red Sox bullpen seemed to be last season, its individual pitchers didn't exactly stand out in the statistical categories that have nothing to do with inherited runners:

Strikeout-to-walk ratio (min. 45 IP)
16. Jonathan Papelbon, 3.17
20. Daniel Bard, 2.86
23. Hideki Okajima, 2.52
48. Ramon Ramirez, 1.63
65. Manny Delcarmen, 1.29

(In case you're wondering, there were 67 relievers who qualified.)

Walks and hits per inning pitched
19. Jonathan Papelbon, 1.147
27. Hideki Okajima, 1.262
30. Daniel Bard, 1.277
36. Ramon Ramirez, 1.335
60. Manny Delcarmen, 1.642

Opponents' on-base plus slugging (OPS)
11. Jonathan Papelbon, .600
29. Daniel Bard, .690
34. Hideki Okajima, .704
36. Ramon Ramirez, .711
56. Manny Delcarmen, .796

Other than Papelbon -- and this is the same Papelbon, don't forget, who allowed more baserunners than usual -- the Red Sox bullpen was a middle-of-the-pack team in all three of the above categories. Manny Delcarmen and Ramon Ramirez both finished the season in the bottom half of the American League in WHIP and opponents' OPS, and not one Red Sox reliever finished in the top 10 in any of the above categories.

The revamped Red Sox defense, it seems, wasn't just about the starting pitchers. The revamped Red Sox defense might be a big help to the bullpen, too.