We can speculate all we want about Anakin not being on form, but fact is Yoda believed Kenobi could destroy Anakin, whereas he said outright he would be useless against Palpatine.
So I am inclined to go mostly with this:
Originally posted by juggernaut74
2. Nobody knew him better than Kenobi.
On top of that it seems clear to me Kenobi is either close to or on Dookus tier. And he does have feats (aside from defeating Anakin) to back that up.