The A's are remarkably skilled at replacing expensive and known players with younger and cheaper equivalents. It is, to some extent, what the A's are aiming to do by swapping Josh Donaldson for Brett Lawrie but whether or not the difference in production is too great it certainly has not been in other notable cases.
Brandon Moss morphed into Ike Davis, who is more affordable, better defensively and more apt to get on base. Don't look now (ok now you can look) but at a fraction of the cost Jesse Chavez is putting up better numbers than Jeff Samardzija.
From spinning Mark Mulder into Dan Haren and Trevor Cahill into Jarrod Parker, the A's have had a knack for identifying players who could seamlessly replicate the performances of their more expensive predecessors.
I'm still getting familiar with Max Muncy's skill set but here's what I have seen so far. Muncy has excellent plate discipline and knowledge of the strike zone. He has some thump in his bat that yields true "alley to alley doubles power" and probably 15-20 HR potential. On the flip side, he is not a good defensive player and he is not fast.
I'm not suggesting that Muncy is potentially as good a pure big league hitter as Butler because in fact Butler, even if he hasn't shown it in Oakland, had a run in his mid-20s of being a far better hitter than Muncy will probably ever be. However, at the same time Muncy has some things going for him over Butler: He is a bit better defensively and by definition of "not being Wellington Castillo" he is faster than Butler.
Muncy also has a genetic advantage over Butler: He bats left-handed. This means that he is on the friendly side of the platoon 2/3 of the time while Butler faces a RHP/RH matchup 2/3 of the time.
What I'm getting at is that the A's could have "done it again" had they not committed $30M to Butler, but instead had given Muncy the DH position. If Oakland could find a suitor for Butler, even if they had to eat some salary, they might be able to get younger, cheaper, and just as good by replacing Butler with Muncy.
What might Muncy reasonably do as the A's primary DH going forward? With his sharp eye, willingness to take a walk, decent slugging, and the benefit of getting most of his at bats against RHPs, I'm beginning to think he could put up a slash line of around .250/.330/.410, giving you a better defensive 1Bman than Butler (taller midget) and less base clogging (faster paraplegic).
Note that the above slash line incorporates some eyeball scouting and projection of Muncy's potential, because his current big league slash line of .213/.286/.387 falls significantly short. On the flip side, his minor league stats might offer more reason for optimism.
The shrewd A's of yore might have passed on Butler and surprised the baseball world yet again with a name no one outside Oakland could cite but who was, as an up-and-comer earning league minimum, ready to approximate the production of a slowly-declining household name.
Again, on a career basis Muncy is not as good a hitter as Butler. However, starting with the advantage of batting LH and then factoring in where they are in their careers, I think it's a reasonable thesis to suggest that the difference between Muncy's batting and Butler's batting going forward is going to be a lot less than the difference in their salaries. Or maybe is just going to be not that different at all, period.