ok, there's some revisionist history going on here. Let me set you straight:
When Lampard arrived in Manchester, it was assumed he was a rotation player for League Cup and low level FA Cup matches, possibly even some league games to provide rotation when there were midweek UCL matches.
The season starts, and David Silva goes down. Yaya decides to start a year long campaign of suck. Fernandinho rambles about the pitch muttering "7 nil 7 nil 7 nil." Then the forwards have injuries: Dzeko is hurt; Jovetic is hurt. Suddenly MC find themselves shorthanded in need of a larger midfield.
In comes Frank. When City are dealt a terrible week of @Arsenal, @Bayern Munich, home at Chelsea, they need Lampard to come in. He does...and he's the hero. He gets more playing time, such that he becomes a key figure in setting up Aguero's hat trick to beat Bayern Munich.
In a season of disappointing midfielders, suddenly everyone in England thinks Lampard is essential to Man City's trophy hopes. It was always ridiculous, but Pellegrini was never going to risk that it wasn't just for NYCFC and Lampard let himself get flattered.
Now instead of coming to MLS as "guy who's getting playing time at a top English contender" he's "guy getting garbage minutes for a team trying to hang on to a UCL spot for next year." It's a disaster for MLS and a disaster for Lampard. Instead of the glowing press he'd get if he had come on time, all he'll get is negative because there's no positive play to offset it. If he waits until August to come, there's a good chance he just gets to sit on the bench because the team chemistry that NYCFC have already established and will only be solidifying in the coming months doesn't leave an easy place for Mix and Frank.
But yeah, MLS just ought to sell Lampard back to MCFC. MCFC need English players especially with Milner waffling on a deal and Lampard seems content with filling .out a roster. NYCFC has better uses for the DP spot.