I'd like to admit from the very start that the Yankees are quite clearly the best team in baseball right now. They're playing confident, consistent baseball at home and on the road. They've got great depth in the lineup, decent depth on the pitching staff, and a solid defense (currently, they're 5th in the AL in fielding percentage). However, as is almost always the case when the Yankees are running hot, there are some audacious claims being made by the Yankee faithful which I'd like to address here.
1.) Derek Jeter is once again the best shortstop in the AL, both offensively and defensively.
There is no doubt that Jeter has made strides to improve his defense since declarations regarding his weakness in that facet of the game became something of a fad among sabermetricians. However, rumors of his resurgence have been greatly exaggerated. Jeter does have a positive Ultimate Zone Rating for the first time since the stat began being recorded in 2001 (quite possible for the first time in his career). However, he is still dead last among AL shortstop in range. His improvement is also assisted by the fact that his double-play partner, Robinson Cano, is also having a career year defensively. Jeter is still clearly inferior to Elvis Andrus and Marco Scutaro, and while his numbers are comparable, I would be reluctant to choose him over younger, quicker, better armed guys like Alexei Ramirez and Erick Aybar.
At the plate, Jeter is on pace for 20 HR for the first time since 2004. He's got his best OPS since he challenged for the MVP in 2006 and he's already got 20 SB, also his most since 2006. Again, notions of his resurgence should be tempered. Like most Yankees, he has been assisted dramatically by the friendly confines of their new ballpark. Jeter's OPS on the road (797) is only 20 points higher than his OPS for 2008. Only 3 of his 14 HR and 18 of his 50 RBI have come away from Yankee Stadium. Jeter remains, as he has been for the last couple years, an excellent contact hitter (.318 at home and on the road) with decent plate discipline and above average baserunning ability. Partially because the AL does not boast anybody on par with guys like Hanley Ramirez, Jose Reyes, Troy Tulowitzki, and Jimmy Rollins, Jeter is among the cream of the crop. However, Jeter fans should note that he trails Jason Bartlett of the Rays in almost ever offensive category (AVG, OBP, SLG, OPS, HR, RBI, SB, SB%, 2B, 3B). His numbers are almost identical to Marco Scutaro's, who doesn't benefit from his home ballpark.
Jeter dedication to improving his defense may mean that he will be able to remain a reasonable starter at shortstop for a couple more seasons, which will save the Yankees from a tough decision, but Jeter is still clearly in the twilight of his career and no longer among the elite at his or really any position.
2.) Mark Texeira is obviously the AL MVP.
Tex is having a great season, especially considering how poor it started and the general pressure of joining the Yankees as a mega-free agent and "future of the franchise" type player. However, let's diffuse the hyperbolic nature of this claim quickly by comparing his numbers to fellow AL first-baseman, Justin Morneau.
Texeira: .288/.385/.565, 71 R, 30 HR, 86 RBI, -0.4 UZR
Morneau: .300/.388/.562, 79 R, 28 HR, 94 RBI, -0.9 UZR
I think it's apparent from these lines that Texeira is not running away from the field, and that's not even considering the fact that Joe Mauer and Miguel Cabrera belong in the conversation as well. When one looks closer at the comparison with Morneau, Texeira picks up another disadvantage. While Morneau has very comparable numbers home and away (988 OPS/13 HR @ Home, 905 OPS/15 HR on Road), Texeira is an entirely different player away from the infamous right-field pavilion at Yankee Stadium (1031 OPS/19 HR @ Home, 867 OPS/11 HR on Road). There's nothing wrong with an 867 OPS. However, if you're going to win an MVP with that number, you better be a Gold Glove winning middle infielder (a.k.a. Pedroia in '08, Tejada in '02).
Tex is an impressive MVP candidate, but it isn't quite time to start clearing room on the shelf.
3.) The starting rotation is the best in baseball.
Yankees starters are 13th in ML in ERA, 12th in innings pitched, and tied for 7th in wins, so clearly this isn't the best rotation statistically. However, clearly what Yankees fans are excited about is the potential postseason rotation of Sabathia, Burnett, Pettitte, and (occasionally) Chamberlain. Sabathia is very quietly turning in another excellent season. His ERA (3.64) is higher than it's been since 2005, but he's on pace for 18 wins and 186 K, which are damn fine numbers. He's also currently on pace for nearly 240 IP. He's gone seven innings or more in 16 of his 25 starts. That's great news during the regular season. However, Sabathia also threw 240+ innings in '07 and '08. His heavy load may be one explanation why his postseason ERA is 7.92. New York would be well served to rest their Ace as much as possible down the stretch, a luxury it looks like they will have, so that Sabathia can enter the playoffs refreshed.
It should also be noted that their #2, A. J. Burnett, has never thrown a postseason pitch, which makes him a bit of a wild card. The Yankees top three is solid, but it isn't noticably better than the trios in San Francisco, Boston, Detroit, Philadelphia, and St. Louis.