When the Yankees and A’s finally get around to playing what is now a two-game set in the Bronx, the series will constitute something of an audition. Whether we like it or not, the Yankee brass will be watching Matt Holliday as he takes his first trip through the Junior Circuit.

Holliday, a career. .318/.385/.549, will be a free agent at the end of the year. He came to Oakland in a trade in November and is attempting to prove that he can hit outside the cozy confines of Coors Field. Yankee Stadium, wind and all, seems like the perfect place for it.

Outside of being an off-season catch for whichever team wants to pony up Boras Bucks for an outfielder turning 30 next January, Holliday may be a trade-deadline acquisition. If the A’s are out of the AL West race by then — and right now, there’s every indication they’ll be among the leaders in that division — Billy Beane could look to get some return for his Holliday investment.

Now this is all well and good, but what does it have to do with the Yankees? Well, two weeks into the season, and the Yanks’ once-vaunted outfield depth has all but disappeared. After we played will-they-or-won’t-they all winter with a trade of Xavier Nady or Nick Swisher, the Yanks lost Nady to some freak accident barely a week into the season.

On Monday evening, the Yanks revealed, well, not much of anything about Nady. The right fielder has gone for numerous tests and second, third and fourth opinions on his elbow. The team is holding out hope that he can rehab it and be back on the field this season. If he has to go under the knife, he won’t play again in 2009, and even if he doesn’t need surgery, his return could be months off.

“We’re ultimately trying to determine if there is an opportunity for a non-surgical rehab because it’s really one of two ways: that way or if you get him cut,” Brian Cashman said to reporters. “If you get him cut, it’s a scary proposition.”

The loss of Nady wouldn’t be unbearable if Hideki Matsui will up to speed, but Matsui isn’t. In fact, there’s no guarantee Matsui will ever be up to speed again. After getting his second knee surgery in as many years, Matsui is off to a slow start. While he’s getting on base at a great clip, he’s just 6 for 31 this season and looks positively anemic on the basepaths. He’s definitely done in the outfield, and last week, he had fluid drained from his surgically repaired knee.

The Yankees, rightfully so, are concerned about Matsui’s health. “The bottom line is that he’s had surgery on either knee the last two years, and you see how at times he’s struggling out there, so yeah it’s a concern,” Cashman said. “He came up with a big hit for us yesterday late in the game which was much needed for him and for us. But yeah, we’re going to have to keep our eye on him, there’s no doubt about that.”

Three weeks ago, the Yankees had too many outfield/DH types for their nine lineup spots. Now, they’re in a situation where Melky Cabrera is their fourth outfielder, and they are a Hideki Matsui injury away from needing a DH. You can never have too much depth.

A-Rod Update

How about some good news before we end this downer injury round-up? According to the AP — who apparently has one reporter assigned to simply watch A-Rod’s rehab workouts — Alex Rodriguez is progressing apace. He hit homers on 10 of his 75 swings today and fielded around 30 groundballs. He is doing some outfield running but hasn’t yet run the bases. When he can slide, he’ll be close to a return.

In a way, tonight’s rain-out was good for the Yankees. It’s just one fewer game they need to play with Cody Ransom at third, and when the game is made up later in the year, A-Rod should be in the lineup.