About 45-50. Remember that the middle sections on the West side have fewer rows (66) than the outer sections. The University took out about 12-15 rows in the early 70s to provide more legroom for the people that paid for the expansion.
I do know not to get under it. The reverb of sound is awful. I about ruined my ear drums there in the Ohio State game.
I now carry concert ear plugs to all games no matter where I sit. No thanks to the ****-crap jumbo one million watt Rolling Stones 3-hour concert you have to endure to get through a game.
I think the 40-45 row boundary is a good one to follow if aiming at tickets.
I've had season tickets in Sec. 2 (south end of west side) for 20 years, ROW 16, near field. Evening games are in the shade there, though not under the upper deck, if that is what you were wondering. So far, every home game time listed as of July 2014, is an evening game.