Bull.
They signed Mahrez for £400k two seasons ago and he's done nothing until this season. Had we signed him we'd have pissed our pants, written him off and called him a Bebe before he got good. For every Mahrez there's 50 transfers that don't pan out and we shouldn't be adopting a completely scattergun approach when we have the money to buy proven quality.
In fact, I'd argue till the cows come home that our transfer activity under Van Gaal/Woodward has been broadly excellent, with the notable exception of Di Maria and Falcao when we have bought we've bought well but, more importantly imo, when we haven't bought we've been vindicated. Case in point, the collective Caf meltdown over Otamendi/Pedro, who have both been pretty shite.