Are you forgetting that Fitz was the main QB in three other games earlier this year (NYJ, Car & Houston)??? In the six games that Edwards played the majority of, TO was targeted 29 times, catching 15 balls. In the five games that Fitz was the QB, TO has had 42 targets, catching 25 balls. So, regardless of who the QB has been, TO has not caught half of the passes thrown to him. It just so happens that Fitz has been throwing to TO more, about 8 times per game v. 5 times per game.
Another thing to figure is that each defense the Bills have played may have been playing TO differently. TO's big week against Jax (9 rec, 197 yrds, 14 targets) could be a large result of what the Jax defense was showing - I haven't studied the game tape so I couldn't tell you that one.
Source of the stats is rtsports.com.