It was the right strategy at the time, but it's not sustainable unless Middleton wants to blow his whole fortune.
Bohm (29) and Suarez (30) aren't going to be core players in 3 years, but trading them to overpay a 30+ year old FA for 6 or 7 years isn't the answer wither.
The good news is when DD was shuffling the roster last summer, he actually upgraded his pitcher prospects and only traded one second tier prospect (Bergolla). So he seems to be wary of moving his top prospects or hurting farm system depth.
Now if they think Sosa/Clemons/Kennedy and eventually Kemp can give them something similar to Bohm, but I can't see more than 1-2 WAR, so that strategy implies the expectation that Bohm will regress.
Trading Ranger raises a similar issue, while his durability in in question, you're then relying on Painter and Walker to fill out #4 and #5, So there would have to be a lot of shuffling.