I got Axisa'd on this yesterday, but with the way the last few games have gone down I did want to touch on the back end of the roster topic while it was still relatively fresh.
The Yankees have definitely over-achieved in these first 27 games. I don't think you'd find too many people who would say they honestly believed the Yankees would be 17-10 with a +32 run differential right now. They've done it by finding a pretty good balance between above-average starting pitching, elite late-game relief pitching, solid team defense, and a return to the "power and patience" approach that served their offense so well for years with just enough speed mixed in. Top to bottom, they're a pretty good ballclub right now even without Tanaka.
What the last few games showed us, especially in the late innings, is that they are also still a ballclub that could use some upgrading at the back end of the roster. True, you can say that about almost any team in MLB, but this is a Yankee-centric blog and it's been those lower-tier guys on the roster who have been killing the Yankees. It's Chris Martin pitching in an important situation and giving up hits and runs; it's Garrett Jones playing first base even though he's a terrible first baseman and not coming up with throws; it's David Carpenter, who for whatever reason is so far outside Joe's circle of trust that he can't even book a flight to get to it, not being able to get 3 outs in a 6-run game; it's Gregorio Petit still being on the roster at all.
Those 4 guys are probably the 22-25 spots on the roster right now in some order, and if you want to throw Esmil Rogers, Stephen Drew, and Carlos Beltran into the mix as the 3 directly above them then you can see that there's plenty of room for improvement. Some will come later today when Jose Pirela is activated off the DL and presumably Petit gets sent down, but when will more come to address those other weak areas? How much longer does Martin have to take up Jacob Lindgren's roster spot? How long will Jones get to do something of value before he gets jettisoned for a Kyle Roller, a Slade Heathcott, or someone else from an outside acquisition?
The Yankees have a pretty good thing going with their everyday lineup and the upfront and way back ends of their pitching staff. They could stand to improve that soft underbelly of the roster though, and I hope they're planning on doing that sooner rather than later. Every game is going to count in the postseason race this year, both in the division and for the Wild Cards. The Yanks can't afford to lose close games at the hands of their weakest roster links.