I would actually be very worried about a huge second half drop off with Vazquez. If you look at his game log, his pitch counts have been ridiculously high, going over 120 pitches and going up to a high of 131 pitches. Robinson is running this guy's arm into the ground, and this makes him a huge risk to become ineffective or get injured. I'm not saying it will happen this year necessarily, but he will pay the price for the workload at some point.
As an example, look at the cases of Mark Buerhle (heavy workload in 2001 and 2002, huge dropoff this year), Freddy Garcia (heavy workload in 2001 and first half of 2002, massive dropoff since then), and AJ Burnett (ridiculous pitch counts last year, went out for the year with TJ surgery). If I had Vazquez, I'd probably trade him for a safer pitcher right now, especially in a keeper league.