That's putting it mildly.
In three games, Cassel has thrown for 571 yards on 45-of-95 passing (47.3 percent) with two touchdowns and three interceptions. His passer rating in those three games - one win and two losses - is 60.5, or, lower than the career completion percentage of Steelers quarterback Ben Roethlisberger.
The most infamous of Cassel's three starts against Pittsburgh came in 2008, the year he replaced Tom Brady for the Patriots, and the Steelers eventually won the Super Bowl. Cassel was 19-for-39 for 169 yards, was intercepted twice and posted is worst in-game rating of the season (39.4).
Steelers defensive coordinator Dick LeBeau generally forces poor performances against quarterbacks going against him for the first time. The Vikings are avoiding that, but few, if any, quarterbacks have had a rougher time against LeBeau in subsequent starts than Cassel has.
Before Tim Tebow foat-passed his way past the Steelers in 2011, Cassel had a very similar performance. With the Chiefs in 2009, Cassel was 15-for-30 for 248 yards and two touchdowns. He managed to not turn the ball over either, as the Chiefs - under Steelers offensive coordinator Todd Haley at the time - pulled off an upset 27-24 victory.
Much of that game was won by the Chiefs' special teams play, as they had three drives with negative yardage, and had 282 yards of total offense, to Pittsburgh's 516.
Cassel was sacked by Lawrence Timmons, losing a fumble on the play, which set the stage for the third time the Steelers saw him.
Timmons picked Cassel off in overtime of Pittsburgh's Week 10 win last year, the Steelers' fourth win in a row at that point. Not only was it the last time the Steelers managed to win consecutive games (they are 2-8 since that game), it was also the game in which Roethlisberger was injured, and forced to miss the next three games.
Cassel was 11-for-26 for 154 yards, no touchdowns and the overtime interception.
Despite average to horrible performances in three games, Cassel managed two overtime games, splitting them. But the most recent was arguably his worst, with the exception of the Chiefs' final drive in regulation, earning a game-tying field goal at the end of regulation.
Which Cassel will the Steelers see - the mediocre one, or the really bad one? That's going to be a key component to determining the winner of this game.
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