Well, it's not so much that the Devil Rays have been playing well, it's more that the Yankees have been playing terribly. Terribly. When Aubrey Huff is stealing bases on you, it's time to look in the mirror.
It's not the bats (the Yankees can still hit), it's the pitching and defense. Having to pull Henn out of Double A (!!!) for a start says quite a lot about their pitching situation for the forseeable future. It appears that Cashman and Steinbrenner made no allowances for injuries this season, rashly assuming that everyone would remain healthy. This extends to the bench as well. What other team has a backup DH? Does Ruben Sierra even bring his glove to the yard anymore? And now, you've got three DHs - Sierra, Giambi, and the Artist Formally Known as Bernie Williams.
What was I saying? Oh right, pitching and defense. I simply don't understand the moves Cashman has made in the field. Not one bit. Everyone knows that Bernie is done as an effective CF, but you don't throw Matsui in there. He played center in Japan, and he was only mediocre. Watch him. He has a terrible jump, takes a circuitous route to the ball, and has the arm strength of Johnny Damon. Still, he's an upgrade over Williams.
The best move was to simply switch Bernie and Matsui. That would've worked for awhile, until Cashman could figure out a better solution. But instead, they throw Tony Womack into LF. Someone explain this with a straight face. He's never ever played LF in his entire life. What's more, they threw Cairo under the bus explicity to let Womack play 2B. Robinson Cano is a better second baseman than Womack? Why is Bubba Crosby even in the system if they don't trust him enough not to put him in LF? Who's even on the Yankee bench? Did their fourth outfielder get stolen along with all those hats? How can a $220 MM team not have a plan B???
Why is this relevent? Because with the exception of Randy Johnson, all of the Yankee SPs rely heavily on the defense to make plays. And the Yankee defense is converting a paltry 65% of balls in play into outs. The league average is in the high 70s. That's not something that's easily correctible, and as long as Womack and Robinson Cano are on the field at the same time, the percentage is going to get worse. They're not going to go on a hot streak against the D-Rays, but they are against the Os, Sox, et al?
Now, I don't think they're dead. They have a tremendous amount of offensive talent, and Rivera can still close games. But it will be a struggle for them, all season. They have yet to win three in a row.