"He’s definitely leading the quarterback ratings in the league, isn’t he?," Harbaugh asked after the Ravens' 23-16 win over the Houston Texans on Monday Night Football.
But Koch's career passer rating of 116.7 ranks as the best in the Ravens' 22-year existence. He's 4-for-4 for 48 yards in his 12-year career.
"Sam is a talented guy," Harbaugh said. "I watch him throw every day. He can throw the ball."
Koch's latest pass was seen as the turning point Monday night. With Baltimore trailing 7-0 in the second quarter, Koch threw a 22-yard pass to Chris Moore to convert a fourth-and-six at the the Houston 41-yard line.
After taking the punt, Koch looked to his right before turning left to lob the ball to Moore. This pass, along with placing five of six punts inside the 20-yard line, earned Koch his second AFC Special Teams Player of the Week award of his career.
Asked how many times he's practiced throwing the ball, Koch said, "Me and Morgan [Cox, long-snapper] have thrown it around on the sidelines a bunch. I’m always like a baseball player. I need to keep my arm warm. It was just one of those things. We called it, we ran it and it was successful."
His passes shouldn't overshadow a Pro Bowl-type season for Koch. He leads the NFL with 29 punts inside the 20-yard line.
Over his career, he's scored a touchdown on a seven-yard scramble off a fake field goal against Oakland in 2012, recorded a two-point conversion off a fake extra point against Pittsburgh in 2011 and rushed twice for first downs (at Cincinnati in 2012 and against Kansas City in 2015). Koch has also made 14 special-teams tackles.
"There’s nothing really that Sam does that surprises a whole lot," special-teams coordinator Jerry Rosburg said earlier this month. "He’s an extraordinary athlete. I mean, he’s the [locker room] cornhole champion. That pretty much says everything!"
Koch's athleticism is a major reason why the Ravens showed no hesitation in calling for him to throw the ball on fourth down against Tennessee on Nov. 5 and against Houston on Monday night.
One more would put Koch in some select company. Since 2001, the most completions thrown by a punter in a single season is three (the Rams' Johnny Hekker in 2012).
"His ability to throw the ball is quite extraordinary," Rosburg said of Koch. "Hopefully, he’ll never have to be an emergency quarterback, but I think he showed everybody how well he can throw the ball."