The Yankees haven't bothered to address their deficiency at designated hitter since Nick Johnson went down, presumably because they've managed to get a .350 wOBA out of the position, tied for fifth-best in the American League. When you rotate the kind of Major League hitters the Yankees boast through the DH slot, you're bound to produce reasonable-enough results; the problem with the rotating DH of course is that you create a complete offensive void elsewhere in the lineup.
When Alex Rodriguez gets half a game off, Ramiro Pena and his .216 wOBA get to waste three to four at-bats that day. When Pena starts a game that also features Francisco Cervelli and the likes of a Colin Curtis or Chad Huffman, you begin to understand (a) why the Yankees' offensive production dipped the way it did in June, (b) that the Yankees haven't sought out a replacement DH is fairly mind-boggling, and (c) why you should be thanking your lucky stars that the lack of punch hasn't significantly affected the team. Given that all indications are that Nick the Injury will be irrelevant for the remainder of the season, it would behoove the Yankees to shore up the designated hitter slot with a real bat for the stretch run.
Yankeeist took a look at some potential DH options back in May, and one possibility that remains relevant is Carlos Delgado, who is looking to sign by the end of July. Delgado may have some life left in his bat yet, and has reportedly been interested in playing for the Yankees previously, so it should not come as a shock if he winds up in pinstripes. At the very least, Delgado doesn't cost any players, and if a deal can be worked out relatively cheaply I see no reason not to take a flier, as Marcus Thames does not inspire a ton of confidence, even if he does have a .376 wOBA in relatively limited duty.
Russell Branyan is having a reasonable year, although I imagine the Yankees would be loath to deal with Seattle after last week's debacle. Other attractive names among non-contenders include Luke Scott (.375 wOBA) and Jose Guillen (.354 wOBA), although there's no reason to think the Orioles or the Royals wouldn't hold the Yankees up for a king's ransom of minor leaguers. Same deal with Jack Cust -- cheap and having a very nice year (.374 wOBA) -- and Yankeeist favorite Adam Dunn -- expensive and having a monster year (.405 wOBA) who would also presumably be too cost-prohibitive to trade for.
It's actually a shame the Nationals aren't doing better, given a huge, breakout season from Josh Willingham -- who I advocated for a few months ago -- and another big year from Ryan Zimmerman. Any of Dunn, Willingham or Zimmerman would be a perfect fill-in at DH (and in Willingham and Zimmerman's case, could also take reps in the field), but again, there's almost no trade scenario that will make sense -- you have to figure Nats' GM Mike Rizzo will almost certainly begin and end the conversation with Jesus Montero, and that ain't happening this time around.
While any of these options would fit nicely into the Yankee lineup and none of these players' teams have any shot at the postseason, unfortunately the likelihood of Brian Cashman acquiring any of them is slim. Unless your name is Kenny Williams, no rival GM is going to want to hand New York a key player for a bunch of junk -- Dayton Moore is probably the most likely candidate to make such a gaffe, but while his free agent signings are generally awful he's never sold off a big-time player at the trade deadline, unless you count Octavio Dotel in 2007. Ultimately Delgado may end up being the most likely solution.