Doesnt matter if he doesn't fit the system , you're argument is based purely on your own opinion.
He (and the rest of the USMNT, but definitely Donovan) has adapted to Klinsmann's system quite well. A lot more possession and attacking. No more parking the bus against the teams that are 'better than you'. You could say that it's been a very Evertonian transition, or that Everton is having a US Soccer-like transition, depending on your worldview.
I see no evidence that says he wouldn't do well under Martinez's system either.
I don't think we'd need him anymore.
Sorry chaps, but the Landon ship has sailed. He was good for us and we made an impression on him, but we had some good times that should be remembered, not tried to be recreated.
Injuries can (and will) happen. When the FA Cup starts up and the schedule gets a bit more congested for us does coincide nicely with MLS's break period.
As the roster sits right now, yeah I don't think it'd be worth getting him either, but I can easily see how the situation would develop.