They ended Yoshida's "nonsense" in LF, too.
Valdez would be a fine DH vs RHPs, which is about 400 PAs a year, with some PH'ing mixed in. He should never play 2B or LF, so that lessens his value to us and to a potential trade partner, but Yoshida is a DH only player, too.
Yoshida hits LHP'er way better than Valdez, but not as well as Refsnyder. To me, haveing a Valdez-Refnsyder DH platoon would be as good or better than Yoshida, on paper, but they take up 2 slots on the 26. That does not make much difference as Ref would still be the 4th or 5th OF'er, as he is now, and Valdez would only DH, like Yoshida does, now.
Anyway, we aren't trading Yoshida, so this is all moot. We should trade Valdez for the best we can get, no matter how little that might be. He is wasting a 40 man roster slot on our DH-only team. Other teams don't have a Yoshida and might want him.