Is Luke Gregerson the real weak link in the Athletics' bullpen?

Last winter, the Oakland Athletics spent lavishly to beef up their bullpen. Billy Beane spent $10 million to bring in Jim Johnson and $5 million to add Luke Gregerson in the hope that closing out close leads would come easily to his team. Johnson, however, has failed spectacularly and has served as a lightning rod for fans' ire as the face of the bullpen's greater struggles. Meanwhile, Gregerson has posted a solid 2.61 ERA and flown mostly under the radar. Here's the thing, though:

A's blown saves: 8
Gregerson: 5
Johnson: 1
Doolittle: 1
Otero: 1

Those eight blown saves are tied with Houston for the most in the American League. And Gregerson's five give him sole possession of the Major League lead. He has literally been the worst reliever in baseball at holding leads, and yet as far as I know he hasn't been booed once by his home fans. Why is that?

There are a few obvious factors. He's making half as much money as Johnson is, and his salary is seven digits instead of eight. He didn't directly replace fan favorite Grant Balfour. His ERA is quite a bit lower since his meltdowns have not been as spectacular as Johnson's, so it's easier to look at his numbers and assume everything is OK. And a couple of his blown saves have come in eighth innings, and those never feel quite as heartbreaking as the ninth inning collapses. But is it possible that Gregerson, not Johnson, is actually the weak link in the pen?

First, let's take a closer look at Johnson. Although his stat line shows just a single blown save, that number should really be at least three; he blew a tie game on Opening Day, and Otero's blown save (on April 9) should have been credited to Johnson in a world with a more logical save rule. Furthermore, he likely would have blown the save on Monday against the White Sox if he hadn't been given a quick hook in favor of Doolittle. But he's only given up runs in six of his 17 games, so he's also had plenty of good outings.

Gregerson, meanwhile, has coughed up runs in five of his 20 appearances and only once allowed multiple runners to cross the plate, but he's shown that giving up a single run can be every bit as damaging as giving up three depending on the situation. You could also make an argument that his blown save on Wednesday should be shared by Fernando Abad, who put the tying and go-ahead runs on base, but the fact that Gregerson served up a home run in a one-run game makes me comfortable with him getting the blame there. He has three saves and three holds to go with his five failures, which means that, when trusted with a close lead, Gregerson is barely succeeding half the time. (Note: That doesn't take into account tie games that he has preserved, of which there are a few.)

There doesn't seem to be anything wrong with Gregerson on the surface. He's limiting hits and home runs like he always has and, while his strikeout rate is down, he's also issuing walks at a rate far below anything he's ever done. His fastball velocity is down slightly, but he's never been a flamethrower and this alone shouldn't be a dealbreaker. None of his individual pitches have fallen off the map by Fangraphs' pitch value metrics, so this isn't a matter of his slider losing overall effectiveness. He's throwing first-pitch strikes at a career-high rate, he's inducing swinging strikes at a near-career-high rate, and he's getting more ground balls than ever.

The closest thing that I can find to an explanation comes within the strike zone. Gregerson is hitting the zone more often than usual, batters are swinging at his strikes noticeably more often, and they're making slightly more contact on those swings. The difference is marginal, but it's not hard to construct a narrative to fit the evidence. For a guy who doesn't throw hard and relies on getting hitters to chase his secondary pitches in the dirt, hitting the zone too often (and having hitters make contact on those pitches) could lead to trouble. Those swinging strikes are likely coming on sliders buried deep in the turf, not on heaters down the middle. But if this was a serious problem, then it would be showing up in the form of more hits or homers.

It would be easy to pin Gregerson's troubles on a change in home venue, but that seems a bit lazy. Sure, he left the cavernous Petco Park, but it's not like he came to a hitter's paradise in Oakland. The Coliseum was not far behind Petco in pitcher-friendly park factors in both 2012 and '13 and, in this year's current small sample, it has rated even worse for hitters than Petco did in any of the last four seasons, since we've only seen the chilly beginning of the campaign and haven't had the hot summer months to balance things out. So, what gives?

There just isn't anything wrong. There are no physical signs to suggest that Gregerson is hurt, and his strong swinging strike rate suggests that his slider hasn't lost its bite. Hitters aren't teeing off against him on a regular basis, and he's not hurting himself by handing out free baserunners given his total of two unintentional walks. For some reason, when it matters most and only then, opponents are finding a way.

I wish I had an explanation for this, though maybe it's good that I don't since most recent explanation for pitchers' struggles have started with "T" and ended with "ommy John." This might just be one of those things that comes out in the wash over the course of the season. And don't get me wrong, Johnson has objectively been the worst pitcher in the pen, having allowed an average of two baserunners per inning. But for now, while everyone else is busy decrying Johnson's gascan tendencies, it will be the sight of Gregerson that raises my stress levels. He's the one who's been blowing all the leads.