I just wanted to throw out some history on Gailey here. All stats came from pro football reference and wikipedia.
In 1988 he was QB coach - then promoted to OC in 89-90. He had Elway at the helm which made him and Shanahan look good. But his offenses were pretty good.
They were 15 in pts and 8th in yards when he took over. In 1989 they were 8th in pts and 15th in yards. In 1990 they were 16th in pts and 8th in yards.
So they were pretty much above average in offense the years that he was QB coach and OC.
His next professional stint was in Pittsburg in 1994 as WR coach. Then in 1996-1997 he was promoted to OC.
As the OC in Pitt. during the 1996 seaon his offenses were 11th in points and 15th in yard with Tomcazk at the helm. Then in 1997 his offenses were 7th in points and 6th in yards with Kordell as the QB. Obviously not the who's who of QBs during that time span - yet fielded above average offenses and obviously got the most out of his QBs. In the 2 years after Gailey left Pittsburg the team plummeted to 28th in points and 25th in yards for the 1998 season and the 1999 season they were 17th in pts and 22nd in yards before the offense got back on track for the 2000 season.
In 1998 Gailey was hired as HC of the Dallas Cowboys
The year before Gailey was hired the Dallas offenses were ranked 22nd in pts and 20th in yards. In came Gailey and the offense went to 9th in pts and 8th in yards for the 1998 season and then 11th in pts and 16th in yards for the 1999 season. Both seasons they went to the playoffs.
He was 18-14 including the playoffs as the HC. They lost both wild card games.
In 2000-2001 Gailey was hired as OC for the Dolphins
Jay Fiedler was the QB at the time. He inherited an offense that was 13th in pts and 20th in yards with Marino at the helm With Fiedler - in 2000 the offense was 16th in pts and 26th in yards and in 2001 the offense was 8th in pts and 21st in yards. Obviously Fiedler is no Marino - but he made that offense click.
From 2002 - 2007 he was the HC of Georgia Tech
2002 7-6 and was tied for 5th in the ACC and lost in the Silicon Valley Classic
2003 7-6 and was tied for 4th in the ACC and won the humanitarian bowl
2004 7-5 and was tied for 6th and won the Champs Sports Bowl
2005 7-5 and was 3rd in the ACC but lost the Emerald Bowl
2006 9-5 and was 1st in the ACC but lost the Gator Bow
2007 7-6 and was 3rd in the ACC but lost in the Humanitarian Bow.
overall he was 44-32 with one conference division title and 2 bowl wins
In 2008-2009 he was hired as the OC for the Kansas City Chiefs
He inherited an offense that was 31st in pts and 31st in yards that had Huard as the QB. He took 7th round pick Tyler Thigpen from the Vikings and made a pretty good looking QB out of him. Improving the offense to 26th in pts and 24th in yards. We all remember the points that KC put up against us - too bad they didn't have a defense worth a darn as the defense mirrored the horribleness that the offense was prior to Gailey's hiring.
He was fired after the first 3 preseason games in 2009 because of scheme issues with Haley.
You can tell that he has had success with offenses in his professional career. He's worked with some very mediocre QBs but gotten good results out of them. He might not be a chic pick - but he's a guy that should be able to make our offense much better.