Travis Kelce only has eight catches through three games this season -- and he's yet to top 100 total yards -- but one of his star teammates, George Karlaftis, is adamant the future Hall of Famer has not lost a step.

The Kansas City pass rusher spoke with TMZ Sports this week about his team's hot 3-0 start ... and while he told us he's much better equipped to talk about the defensive side of the ball -- he knows for a fact Kelce ain't washed.

Karlaftis said straight up the tight end "hasn't skipped a beat" -- and even though critics have suggested TK's highly publicized offseason with Taylor Swift has caused his slow start ... Kelce's teammate's seen no change in the 34-year-old's preparation process.

"He's a guy that loves football," Karlaftis said. "He's going to come and work his tail off every single day no matter what."

Karlaftis appeared to point toward all the double and triple teams Kelce has seen this season as the biggest reasons for his decline in production.

"Teams have to respect him," Karlaftis added. "He's the greatest tight end to ever play, you could argue. Certainly I think so."

Seems Patrick Mahomes would agree, as following the game against Atlanta on Sunday night, the QB told reporters teams are simply doing everything they can to take Travis out of the game.