Be careful about hitting your peak value with the A's because the moment you do, you will be traded by ...well, fans who like to propose trades. And sometimes by the team itself but not always.
Not all peaks are equal, folks. There are some players it makes great sense to "sell high" on and others where this practice is foolish. Just because a player has a great year or a breakout season doesn't mean the best move is to ship them off elsewhere. You might actually want to reap the benefits of their talent. Just not always.
A great example of a smart "sell at peak value" was Guillermo Moscoco, whose mirage-y breakout season was aided by the Oakland Coliseum's forgiveness of fly balls to the wall and who was an excellent candidate for a "one year wonder' career. The A's made a great move selling Moscoso's and Outman's good
seasons statistics for the underrated and useful Seth Smith.
In contrast, I really don't want to start yet another debate on the Josh Donaldson trade, but what's notable about his situation is that he had 4 cost-controlled years remaining on his contract and was performing at such at a high level that he had ample room to fall and still maintain his status as an elite, or excellent, player.
Avoiding that bag of worms, though, let me divert the focus to a somewhat similar player: Sonny Gray. Gray may or may not have peaked with his sensational 2015 season. What we know is that at 25, he is not yet at the age where one would naturally predict a steady decline, he is performing at a star level, he has 4 cost-controlled years remaining on his contract, and he could slip a notch without falling to "just good". One notch down from where Gray is now would best be described as "only great".
Of course Gray could get injured, but there is nothing at the moment to especially predict that he will other than the fact that he powers fastballs and snaps off curves, and all pitchers are injury risks. Rather than deal Gray at high value, the A's have another option and that is to enjoy the benefits of having such a good pitcher for 4 more cost-controlled seasons.
There are, however, a couple "sell high" candidates on the current A's roster.
I would put Danny Valencia squarely in that category, as someone who had a suddenly good season but who, in order to repeat it, would have to slug against RHPs in a way he did in 2015 but did not do in 2010, 2011, 2012, 2013, or 2014. What Valencia has always been is a guy who plays an average 3B, hits LHPs very well, hits RHPs poorly, and has a shaky clubhouse reputation.
What changed in 2015 is that he slugged .556 against RHPs (still reaching base at only a .325 clip) and that helped him produce much better overall stats than usual. What I would expect from Valencia, in 2016, is a regression to slugging around .400 against RHP (his career mark, even after 2015, is just .389), which will bring his overall slash line down closer to his overall career line of .267/.310/.426. With average defense and a bad attitude. Let someone offer value for him and sell high, and thank Valencia for his most excellent John Mabry impression.
Another future candidate is Jesse Hahn who, if he has an excellent 2016 season, could have real value in a trade. Hahn has already had one TJS and last year had elbow pain that scared the A's into thinking he might need a second TJS. Luckily he didn't, but Hahn's career is following the Jarrod Parker path: coming to the A's with one TJS in his back pocket and possibly a ticking time bomb to go down for another 1.5 years only to come back probably as a reliever-if-at-all.
If the A's trade Hahn following a strong 2016 season, as difficult as it is to see quality cost-controlled SPs dealt I will see the wisdom in it because if he's not traded for value he is a strong candidate to wind up giving you nothing on the mound and nothing in trade.
Now of course, Valencia could out-perform Brett Lawrie for the next two seasons, Hahn could stay healthy and carve out a great career, and Gray could be the one to go down with a crippling injury. The only "known" in baseball is that there is mostly the unknown.
Gray, Hahn, Valencia, Lawrie, Vogt, Phegley, Burns, Reddick, Graveman...Who do you see as the best "trade at peak value" players and who do you see as the "keepers"? It's an inexact science to be sure, as every GM has learned the hard way.