LOL. I don't know where you're getting 6 out of 8 years (McCarthy's obviously been a head coach for much longer that that), and I don't give a shlt how you want to interpret who PFR might list as "starters." For example: In 2010, somebody named Korey Hall is listed as starting for the Green Bay Packers, at fullback. He had zero yards rushing and 1 catch....for the entire season. That same year, James Jones had 50 catches for 679 yards and 5 touchdowns, operating as WR3 behind Driver and Jennings. Are you going to tell me that they were a 21 personnel team that year and not 11? Again, LOL. Talk about insanity.
McCarthy runs a west coast offense. He ran 11 personnel 76% of the time during his last season in Dallas. Yeah, he drafted Cobb way down in the second round...when he already had three solid receivers. The Steelers don't. But tell me again about what you read and misinterpreted on pro-football-reference. It's so compelling.