First of all, English is not my native language, so sorry for any mistake I make. I bought Delaney IF very early, about one week after he got his card and I always played him as CB, where he was quite good already. But the longer I played him, the more I recognized that he is not fast enough anymore for a CB, even with Anchor or Shadow. And a few days ago I finally bought Zakaria RTTF, who I would also recommend, and made the decision that I swap them ingame (I play 4-2-3-1). So Zakaria plays as left CB and Delaney plays as left CDM ingame. And HOLY JESUS is he good! The first game I played him as CDM he won 12/15 tackles (more than the rest of my squad together!), played 22 successful passes an had 3 assists. He is the best Bundesliga CDM I played and I nearly played every good one. I still can't believe how good he is. And he is insane at scoring headers after corners for some reason.
DISCLAIMER at the end: His stats (games, goals, assists) aren't represantative beacause i mostly played him as CB.
-Nearly everything, doesn't really have a weakness.
-Maybe pace if you play him as CB
(-Shooting, but doesn't matter, his headers are very good)