I do think expectations were a little high for them this season. They won the CL by being defensively superb and very well organised, but in the league they were dropping plenty of points. Lukaku alone wasn't going to remedy this, they're just not as good going forward at all as Liverpool or City.
And he 100% has piled back on weight lately. I know he had a special diet at Inter but holy shit, there has to be other factors. It was the exact same problem at United where he looked like he wasn't moving right at all.