A "good tackler" refers to a person who is skilled at stopping or bringing down an opponent in sports like football or rugby by grabbing them effectively. Full definition
He's a very good tackler in the open field and is known as an intelligent player.» (thephinsider.com)
Gibbs, if encouraged, is a very good tackler with pace. (justarsenal.com)
That leaves one position to fight for, and your man Henderson barely loses or misplaces a ball, good tackler too, Lallana can play there. (justarsenal.com)