The phrase "excellent tackler" means someone who is very skilled at stopping someone from moving forward in a sport, especially by grabbing or knocking them down. Full definition
Lastly, how good were Mustafi and Kos, excellent tacklers of the ball. (justarsenal.com)
He's an excellent tackler, which is another thing you look for in a linebacker. (sportstarsmag.com)
AD: Rodri is a tremendous young talent — he's someone who is great at recovering the ball, an excellent tackler and good in the air. (intothecalderon.com)