The numbers (and the eye test) speak volumes about his play:
In 375 MLB PA Engel is slashing 168/243/276 for a wRC of 40. This year he's improved his slash line to 188/308/219 for a wRC+ of 60.
In addition to his well know struggles at the plate Engel has struggled in CF with bad routes, weak throws and lapses in concentration. He's -1.8 runs according to Fangraphs so far in CF.
All in all he's been worth -1 fWAR in a little over half a season of MLB play. If you squint maybe you can see a productive 4th OF but at what point does the org pull the plug on the Engel as starting CF experiment? It would be one thing if he was a guy with a history of success in MilB but that is not the case either. In his last AAA stint Engel hit .218, his overall line buoyed by a flukey .256 iso. His hit tool makes Yoan look like Ted Williams.
With the presumed 3-4 month injury to Cordell perhaps Adam was granted a temporary reprieve last night. That said, those that have followed him closer -- is Tilson ready? [from a quick glance at the AAA stats, no, he's not.]
How about Leury as starting CF? Do the Sox have someone ready to come up into a utility IF role, or do you simply make Tyler the primary backup at 3B, SS and 2B with Yolmer providing emergency cover?
Personally I'm more than ready to move on. I don't see any upside to giving Engel more PA and I'd much rather see them go to Leury.