Not underestimating. They WERE all excellent players but three of them are in their mid 30s now. Mirallas on his day is excellent, no doubt. Those days are far too spread out though, reminds me of Puncheon or Bolasie at Palace.
I think he will do alright, the problem is £100m was a lot of money when Abramovic took over Chelsea. Now though, it wouldn't get you Stirling, Mangala and Lovren. You will be up there with us, Leicester, Liverpool and West Ham, fighting over 6th and 7th in all likelyhood, whilst a revived Chelsea and Utd battle it out with City, Arsenal and Spurs for the title.