This diary was originally going to be called The Heteronormative Kinship Relationship of Jim Harbaugh and Tim Drevno and Its Representational Role in the Construction of Masculinity in the Academy Around the Body-as-Athlete.* But that ended up seeming pretty long.
The board is - as you've no doubt observed - very down on Drevno. What is posted below is offered as evidence that Harbaugh has reason to be loyal to Drevno as an offensive line coach (maybe especially as a producer of lines that can run the ball). It is not offered as evidence that Drevno is a good offensive coordinator or recruiter.
Drevno became Stanford's OL coach in 2009. This was the first year Andew Luck started and the year that Toby Gerhart was a Heisman finalist.
Stanford's offense jumped from 31st in the S&P+ rankings (gaining 351.8 ypg) in 2008 to 6th in those rankings (gaining 427.6 ypg) in 2009. The Cardinal were the 11th ranked rushing team. Luck and Gerhart were a major part of the offense's improvement, but Drevno's OL hardly held them back.
Stanford's 2009 OL featured a first-team all Pac 10 tackle (Chris Marinelli) who was also second team All American, a second team all Pac 10 center in Chase Bealer, and three honorable mention all Pac 12 players (Jonathan Martin, David DeCastro, and Andrew Philips). DeCastro and Martin were first year players.
Stanford's offense took another step forward in 2010 despite losing Gerhart, finishing 3rd in the S&P+ rankings (gaining 472.5 ypg). This was the year Luck became a clear high first round draft pick, and I don't mean to minimize that at all. But again, Drevno's OLs hardly lagged behind their fellow offensive players.
Stanford's 2010 OL helped it get to 17th nationally in rushing yards. And they gave only up six sacks. This bears repeating: they gave up only six sacks!
Stanford's 2010 OL featured a first team All American and first team all Pac 10 center (Beeler), two other first team all Pac 10 players (DeCastro and Martin), and two honorable mention all conference players (Andrew Phillips and Derek Hall).
To put Stanford's 2010 OL performance in context, Alabama has fielded three first team all conference offensive lineman only twice during Nick Saban's tenure (I won't argue if you want to say that this is harder in the SEC than it is in the Pac 10/12). Also, all of Stanford's offensive lineman in 2010 (and 2009) were three-star guys coming out of high school. The overall player rankings per 247 of the six lineman who started on the Stanford OL in 2009-2010 are as follows: Martin (459), Marinelli (735), DeCastro (360), Beeler (391), Hall (rated as a WDE)(810), and Phillips (934).
In 2011, Drevno followed Harbaugh to San Francisco, where he stayed until 2013. Drevno's record in SF was mixed.
The Niners went from 24th in total offense in 2010 to 26th in 2011. They then improved to 11th in 2012 but dropped to 24th in 2013.
The Niners had no Pro Bowl offensive linemen in 2011, but they fielded one (Joe Staley) in 2012 and two (Staley and Mike Iupati) in 2013.
The line's statistics in 2011-2013 were admittedly up and down - and the line was never good at pass blocking. The 49er OL dipped from 13th in adjusted line yards in 2010 to 21st in 2011, but it improved from 30th in sacks yielded to 21st. In 2012, the line jumped to 1st in adjusted line yards but dropped to 29th in sacks yielded. In 2013, the line dropped all the way down to 29th in adjusted line yards and ranked 22nd in terms of sacks allowed. Those 2013 stats are slightly odd in light of Staley and Iupati making the Pro Bowl.
Harbaugh stayed in San Francisco for 2014, but Drevno went to USC. There he helped the offense move from 59th in the S&P+ rankings in 2013 (gaining 399.1 ypg) to 18th in 2014 (gaining 457.6 ypg). His OL also featured a first team all conference player (Max Tuerk), who had been honorable mention all conference the year before, and two true freshman players (Toa Lobendan and Viane Talamaivo) who were given honorable mention all Pac 12 honors.
The Trojans were 68th in rushing nationally in 2014. They gave up 32 sacks (7th best in the Pac 12 and a slight improvement on the 34 they surrendered in 2013).
I assume everyone is acquainted with what Drevno has done at Michigan, so I'm not going to cover that (I'm also running out of time and energy to work on this thing).
Taking all of the above together, Drevno came to Michigan having produced at least one truly excellent line (2010 Stanford) and one really poor line, albeit one that had two Pro Bowlers (SF in 2013). But it seems he produced more very good to good(ish) lines (Stanford 2009 and SF 2012) than bad ones (SF in 2011). And his production at Stanford and USC was with middling recruits (Stanford) and true freshman (USC). So my takeaway, as I said above, is that Harbaugh can justify his loyalty to Drevno as an OL coach. This seems especially true if we're talking about run blocking and maybe (see below) not so strong a statement if we're talking about pass blocking (2017 Michigan says hello). You are, of course, free to agree, disagree, or somehow squeeze a Jim McElwain shark joke into this.
One more thought: It was surpsingly hard to find information about sacks allowed for Drevno's time at Stanford and USC. I could not find any information on that for 2009 Stanford or anything more than what I posted re: USC's 2014 pass blocking. I also couldn't find sacks allowed for 2008 Stanford in order to compare them to 2009 Stanford.
*This joke will be much better if you were part of the "Michigan hosts pro-pederasty talk" thread that was caved earlier this week.