CHARLOTTE, N.C. — By trading with the Cleveland Browns for quarterback Baker Mayfield on Thursday, Carolina instantly adds competition to its quarterback room of Sam Darnold, PJ Walker, rookie Matt Corral and the undrafted rookie Davis Cheek. In exchange for Mayfield, the Panthers agreed to trade a conditional 2024 fifth-round pick; that pick becomes a fourth-round selection if he plays around 70% of offensive snaps this season. Mayfield and Darnold — who were the Nos. 1 and 3 picks in the 2018 draft — will enter training camp with an open competition at quarterback, according to a league sour…
