Soldato
Its all to do with setup and tactics rather then ability though, Iniesta scores a lot more frequently for spain then Barca .. but you wouldn't say he's really playing better.
True that, Gerrard deployed behind the striker, Lampard given free license due to having the likes of Makalele, Mikel, Essien covering for him, even Scholes in his 20 goal season was when he was playing behind RVN, before that I think he generally was around the 10-15 mark
And like you said what these teams have in playing a midfielder with free roam they lack in width/wingers (Chelsea maybe not so much as they have Cashley)