That last bit about Abraham is not proven so until we actually win the title or at the very least, challenge for the title with him leading the line. He also needs to prove as well that he can be consistent at the highest level week in week out. Last season, his form fell off the cliff after the first few months and we didn't even challenge for the title, although admittedly, he was overplayed.
Also, how sure are we that the team is only better when Abraham plays through the middle? How many games has Werner been used through the middle? He played there against Southampton and did well. He played there against Sevilla and at Man United but we set up to get a draw or were too defensive. And he hasn't been used through the middle since we switched to this 4-3-3, apart from the last 20 minutes at Krasnodar.
It's also worth mentioning that we didn't buy Werner just to stick him out of the left every time and I don't think we'll play with 2 strikers unless we play a back 3. We need to avoid pigeonholing Werner as someone who only shines when there is space to run into. He has developed his game in the last 1-2 years - and is improving - to get more involved in buildup plays, dropping deep to link up the play, to create opportunities for others etc.