Time for pitching! Huzzah for some of the team's strong points. Alright, one of the team's very few actual strong points. StatCorner uses tRA to judge pitching and therefore the series previews use tRA and therefore these graphs use tRA (actually an offshoot* of tRA).
*pRAA = (league's tRA - pitcher's tRA) / 27 x pitcher's expected outs recorded
Here is last season's starting rotation post. 2010's graph looked like this:
From the beginning, the Mariners' rotation seized the lead on the team and though they dipped in the second half, the collective unit never dropped into below average territory. That dip mirrored a bit was what seen in 2010 when the middle of the season saw the departure of Sir Cliff Lee and his gentle smile while 2011 had us fans bidding adieu to Erik Bedard and Doug Fister which chopped the good part of the rotation in half. Also, oh man, Anthony Vasquez, your pitching makes it difficult for anyone to join the AV Club.
Just for enlightenment purposes, I re-did the 2011 graph from 22 August onward and replaced all of Vasquez's starts with a league average performance. Just so that you could grasp how much of an impact he had even over such a small time period.
Later this winter, King County officials will announce that the stretch of Interstate 5 between Tacoma and Seattle shall forever on be colloquially referred to as The Vasquez Gap.