I think the strategy for now is to let him be a butcher in the OF so we can get a longer look at his bat. If you give up on his glove so much that you don't play him in the field, you are taking ABs from Davidson who has out-hit him this year and has a similar pedigree. The optimal lineup for winning right now would probably be Yolmer in LF, Davidson at 3B, and Palka at DH, but Yolmer playing outfield is more hypothetical than anything else right now and Davidson's 3B defense is somewhat of an unknown quantity by now.
I worry about a guy who is on a hot run with no walks, though it's encouraging that he has hit the ball so hard. The comparison to Delmonico isn't perfect because there were signs last year that Delmonico was on a lucky run. Look at the hit probabilities on Nicky's homers: most of them were worse than 50/50 and his average exit velo was not good.
The main negative with Palka for now is that his defensive problems affect more than just his fWAR, it hurts our pitchers too. A couple of our young starters have had outings undone partly by bad plays from Palka. I think we're going to just tolerate that for now, hope he improves, and hope that the continued exposure helps us figure out what he's got.
A final note about his minor league track record: It's not great, at least lately. Summarizing:
2015 in A+ (129 G): .890 OPS, 29 HR. 29% K%. Also, 24 SB????
2016 in AA (79 G): .890 OPS, 21 HR. 29% K%.
2016 in AAA (54 G): .780 OPS, 13 HR. 39% K%
2017 in AAA (84 G): .760 OPS, 11 HR. 22% K%
2018 in AAA (17 G): .860 OPS, 3 HR. 29% K%.
What stands out to me is that he hit a wall in AAA and hasn't really produced at that level. This was predictable from his high K rates at the lower levels where his overall numbers were still good. There was a positive development last season despite his worse production in that he did cut his strikeouts. They were back up this year in AAA but the sample is small and the difference from last year wasn't large. Strikeouts haven't been a major problem in MLB.
Still, I'm always suspicious of guys who hit better in MLB than in AAA until I've seen them do it for a while or if they were called up young/inexperienced.