2 wins and 18 podiums since the comeback and this earns one a place in the 'Least successful comebacks' thread. It's like some people are clinically unable to give Kimi any credit even when he's done something right.
Actually I have to agree with you here. We need to define, what success is.
I mean... We may discuss whether the Lotus car had a bit more potential in it than Kimi ultimately delivered, but there is no way Kimi's Lotus career wasn't a success as such. Third in WDC and lots of podiums is very much a success. Also performance-wise I'd say he was among top 5 drivers on the grid at that time too (even if not level with Alo, Vet, Ham), so that's also very good.
Conversely... Schumacher's comeback was not a success. Yeah, again we may discuss whether his performance wasn't that bad, but in the end he got just 1 podium, was stuck in average cars and got beaten by Rosberg in all three years. For a 7xWDC this very much is NOT a success!