Murray's run at slams from 2011 AO - 2013 Wimbledon
F, SF, SF, SF, SF, QF, F, W, F, (A), W.
His losses during that run are to Novak, Nadal, Nadal, Nadal, Nadal, Ferrer, Fed, Novak, respectively.
"Never that consistent" still puts Murray in a rarefied level of consistent GS performances.
Even the two slam semi-finals he's lost to non-big 3 members were to slam winners.
Obviously the fallacy is to assume that he unequivocally would've beaten any non-big 3 players in the matches he lost but his win-loss records at slams suggests he would've at least won most of those.