Rivera's understudies have been shaky

Yes, Mariano Rivera's doing it again. No, he's not a robot.

Meanwhile, the second line of defense is more than human, as Joba Chamberlain, Dave Robertson, and Damaso Marte have all had their rough patches. And don't think they're not just a little sensitive about it.

"We're doing the best we can," Robertson said. "We've got a great group of guys out there. We have our bad days just like every other team has their bad days. But I think we're doing a good job, giving it everything we've got."

Chamberlain lost the fifth-starter race to Phil Hughes in spring training and has had a handful of rough outings, leading to a 5.29 ERA over a team-high 34 appearances through Tuesday. He had allowed one run in his last four games.

"My season is great," Chamberlain said. "You guys will focus on the four bad ones. I'll focus on the 28 good ones that I had. That's the way you have to look at it. You're always going to focus on what goes wrong, but you're never going to write what goes right. I understand that and everybody else does. I just continue to get better every day and focus on what I need to do to help this team win.

What I don't like about the Yankees' non-Rivera relievers: Chamberlain's 5.29 ERA, Robertson's 5.04 ERA, Marte's 11 walks in 15 innings, and Chan Ho Park's (gulp) 6.48 ERA.

What I do like about the Yankees' non-Rivera relievers: With the exception of Marte (who's pitched only 15 innings), all of those guys have solid (or better) strikeout-to-walk ratios. Bullpen ERAs are systemically fickle, due to the small sample sizes. Joba's going to be good, and the others should be serviceable.

Is "serviceable" enough, though? If you're the Yankees, don't you want one more lights-out reliever? Or a situational lefty you can really count on? You know the Yankees will do something this month, and there aren't many holes to fill. A left-handed bat would be useful, and I suppose there's always a chance the Yanks will tire of A.J. Burnett or Javier Vazquez, and go after a big-name starter.

That seems unlikely, though. There are always bullpen arms available in July, and it'll be a small upset if the Yankees don't grab one or two of them.