We already had Gregory Soto once and it didn't work out for us. I don't know which outfielder we would dump to lock up Santander—I assume you mean Carpenter, but I don't think Santander is any more of an advantage for us in right field, and I don't think we're in the market for a minus right fielder to replace another one for big bucks simply because he's on the other side of the plate. Teoscar, same thing, plus he had a full season of 108 OPS+ just a year ago, so I don't know that he's necessarily guaranteed to be much better than that at ages 32+.
I like the idea of Christian Walker. Plus defender, 20-plus-homer threat from the right side in Comerica, already playing the position his age requires anyway, and we should be able to get him relatively cheap, meaning, no more than three years guaranteed.