Voit is also 32 years old an no signs that he's changed anything that would be worthy of another chance in MLB, after he was given one, again, this year. He's at the age where there is no upside and likelihood of improvement/change is very low. The other guy is still very young where improvements/changes/adjustments still happen all the time.
If Keston had made no changes to his approach/swing and continued to mash AAA like he has in the past I'd be more on the 'why would we expect anything different this time" view this poster has. However, he has made clear noticeable changes in his approach where it is logical to think it's possible for improvement at the MLB level. Of course its also a large possibility he remains a low BA/high K guy with power that is frustrating and not quite good enough. But a marginal improvement on his contact is all that is needed to move him from fringe player to positive starter. But really the main point is even his last 2 years of subpar performance is still better than the trash they've ran out at DH/1B this year. IMO, once I saw here on the contract quirk for next year I think they're so close to the end of the season that they don't think its worth blowing that option. Say he didn't have that injury maybe they'd have been open to giving him a chance with WInker and others being so bad, but once it got this late they might want to get to next year and try him as a very cheap DH (as opposed the the 8 mil one this year and last who both sucked).
Also, after the deadline there isn't really as urgent of a need for him as there was say in June, they addressed it with trades. Canha is a competent hitter and will get tons of DH ABs. Rowdy is back and rightfully will be given a chance. Rewind like 8 weeks and you had 0 good hitters at 1B/DH. You now have one good-ish, one competent, and one you're hoping bounces back
I'm generally on the side that current management deserves the benefit of the doubt on things, but that doesn't mean they don't get things wrong. And when it comes to assessing offense and building a competent offense, let's just say their expertise is lacking on that side of the diamond. When it comes to pitching, everyone should pretty much no comment though.