Quality of coaching and professionalism of footballers in England has improved considerably in the last ten years, but "players run a lot more these days" always sounded dubious to me. Top PL players in this era are averaging 10 - 12km per game (with some hitting 13km for certain matches) which is roughly the same as what players like Gerrard and Rooney were averaging over 15 years ago.
Prem games are less manic and back-and-forth these days if anything.