It's easy because it's true. The difference in individual quality of players we have now compared to 10-15 years ago is night and day.
Cahil and Smalling are decent CB's but we had an incredible group of CB's back then. Walker and Rose, if you're clutching at straws, might have made the squad as cover but they're never getting into the side ahead of Neville or Cole.
Midfield is the biggest difference for me though. We've gone from having some of the best midfielders in the world to nothing. We have one natural central midfielder in Wilshere and even a fully fit Wilshere isn't nearly as good as Lampard, Gerrard or Scholes and would have struggled to make the squad in their era. The fact that we've taken Wilshere despite not kicking a ball for a season highlights how bad the rest are. Dier should never be making an England squad as a midifielder - maybe as a utility player - but to be starting as our first choice CM is an embarrassment.