Masthay is not a top 5 in the NFL punter, but is one of, if not THE best punter that has been a Packer. His career avg. is 44.2 yds/p, and in '15 was 43.9. 2014 was his statistically worst year, but the offense scored so much that he only punted 49 times, with a few games with zero punts. He punted 81 times in 2015 and had career low return yards/punt allowed, career high net yards and most kicks out of bounds.
We don't know what his instructions were from Zook, but other teams didn't light-up the punting units as has happened in the recent past. Would we like to see more fair catches at the 10 yard line? Heck yeah. When the offense stalls at their own 20 would we like Masthay to boom a 60+ yarder EVERY time? Heck yeah, but he did his job pretty well regardless of what some fans think.
FYI - Craig Hentrich was "the one that got away" which was a regret of Ron Wolf for not re-signing. Hentrich's Packer career long punt was 70 yds (vs. Masthay's 71) and avg./punt as a Packer was 42.8 yds (vs. Masthay's 44.2 yds).