To be honest, I'm not bothered. I don't think for example, he's better than Falcao was for them. I don't think he's one of the top strikers in the world, he just plays in a system that suits him. Wouldn't surprise me to see him struggle.
Or is that just wishful thinking?
I don't think he was better than Falcao was for Atleti - the side Falcao played in was vastly inferior, even if there were many familiar faces. They were a totally average side who relied on Falcao, & Falcao only, to deliver the goods (and he did so, every week. The difference is, he would score and they would draw or lose, whereas Diego Costa is doing the same, but he has the team around him to win games and challenge for silverware). Falcao scored goals from nothing - I think his move to Monaco has (understandably) made people forget how good he was/is. Falcao at Atletico was like a much, much more extreme version of Van Nistelrooy at United. He was the definition of world class.
Costa will fit Chelsea like a glove, he is a Jose type of striker, but I do think he is still below the 'world class' bracket. He needs to prove he can sustain this form for over a year. Atletico have probably been the best
team (as in, how the players have worked together like a well-oiled machine, no superstars, & executed their manager's game plan) in the world this season - Costa has been brilliant, but any very good/quality striker will have had the season he has had when all 10 of your teammates are programmed to make you score a goal. I am not discrediting him, he is a brilliant player, but he has received some great service in a system where he is the spearhead. Any less than 25/30 over the season and one would be disappointed (with few goals from midfield), considering they are title favourites & in a CL final, i'd say. If he can prove he can do it again without Simeone, then by all means I would understand people calling him world class. He's no Falcao, though. Just my opinion, but he's miles behind Falcao. That guy was born to score goals.
Very good price, I think he's a great player & i'd be surprised to see him fail to tear it up in the league. He really suits Chelsea, too. I think he'll score over 20 in the league.