On a side note, but I can’t believe anyone would actually think a coach would pick a player on name. Yet it’s an argument that pops up.
From a coach perspective, even a kids football coach, it’s fairly obvious that any coach will trade off the question of form with the questions of tactical relations (who functions best together in the way we play) and team tactics (how do we want to play against Villarreal specifically).
Solskjær sees the boys in games or training every day and week, he knows what form they are in, what capacities they bring and how they work in different set ups. That will decide.
Rashford has the speed and the ability to threaten on the shoulder that will greatly affect the tactical battle regardless of form. Other teams adapt their tactics to Rashford, sacrificing some of their own strengths. That weighs against what both Pogba and Grenwood brings to the attack. He has built good tactical relations with Shaw and Bruno in the RW position. That weighs against Pogba’s better form.
If Rashford plays on the right of Cavani in the final, it’s because the coaches have weighed the sum of these parts and found United stand a bigger chance of winning that way.
Personally, I would probably play Pogba on the left against Villarreal, as they are not used to defending Rashford, they will probably lay low and exploit errors in midfield to overpower our defence quickly. Pogba brings errors in midfield and is not good at defending counters. Greenwoo dwill be better, but he is not as good at opening space in tight, low blocks against technical defenders, so I would start with Pogba and bring Greenwood on later if needed. Wether that would be better than Pogba in midfield I think is almost a coin toss, but I’d definitely prefer it to Pogba on the left, sacrificing Rashfords specialities, almost regardless of form.