What evidence do we have that he is actually a good OL coach? Going back to 2009, below is how his teams ranked across a few stats. Philbin wasn't the OL coach specifically for all of these teams, but given his background as an OL coach, I think it's fair to look at them because his finger prints are all over the OL in some form or fashion (his scheme, his coaches, etc.).
2009 (GB): 8 (QB hits allowed), 1 (sacks allowed), 11 (yards/carry)
2010 (GB): 23 (QB hits allowed), 11 (sacks allowed), 27 (yards/carry)
2011 (GB): 18 (QB hits allowed), 11 (sacks allowed), 27 (yards/carry)
This was during his time with Aaron Rodgers as QB...a very mobile QB with tremendous pocket presence. Yet they were still mediocre in pass protection. And despite having arguably the best to ever play QB, they couldn't run the ball. Philbin was the OC during this time, but it was his scheme...and he had previously worked with their OL coach for years.
2012 (MIA): 24 (QB hits allowed), 14 (sacks allowed), 20 (yards/carry)
2013 (MIA): 7 (QB hits allowed), 1 (sacks allowed), 20 (yards/carry)
2014 (MIA): 5 (QB hits allowed), 10 (sacks allowed), 2 (yards/carry)
2015 (MIA): 5 (QB hits allowed), 8 (sacks allowed), 10 (yards/carry)
Philbin was then hired by MIA to be their HC...so he actually hired the OL coaches to install his blocking schemes. He had two OL coaches during his MIA tenure...Jim Turner and John Benton. Turner was fired after the "Bullygate" scandal involving the OL (which all happened under Philbin's watch)...and is now back at A&M as the OL. Benton is now the 49ers OL coach...the only team with more QB hits than the Colts this season. Not exactly a great coaching tree there.
2016 (IND): 2 (QB hits allowed), 5 (sacks allowed), 20 (yards/carry)
2017 (IND): 2 (QB hits allowed), 1 (sacks allowed), 28 (yards/carry)
We all know the story here...but since Philbin showed up in Indy, the OL has been nothing short of atrocious. They are in a three-way tie with SF and CLE for the most criminal pass protection over the past two seasons, but those teams actually have top-tier run games, while the Colts have been a bottom-tier team. So I think it's fair to argue that the Colts have the worst OL in the NFL since the start of the 2016 season (when Philbin got here). I have yet to see any indication that it's going to improve.
I just don't know what proof there he is actually a good coach...especially on the OL. In GB, he had a very talented offensive team, including a HOF QB and several good-great OL players (Chad Clifton, Scott Wells, Josh Sitton, T.J. Lang, Bryan Bulaga)...and the OL results were still mixed. I would like to think he had a hand in helping at least coach up some of those individuals, but we have yet to see any of that on the Colts...so it's hard to say for sure. In MIA, he yet again had some decent talent on the OL (Mike Pouncey, Branden Albert, Richie Incognito)...and again the OL wasn't very good. And then you have IND...where he doesn't have talent and the results are terrible.
Much like Chud, I have no doubt Philbin is respected in some (or more) NFL circles. But at the end of the day, the Colts need to get this guy out of here.