By Alek Arend Baker Mayfield is taking his offseason training very seriously. The current Browns quarterback has hired a new quarterbacks coach. Why is that significant? Because it’s the same quarterbacks coach who works with Patrick Mahomes. Mayfield is working with Jeff Christensen to improve his mechanics and throwing motion. And although the former No. 1 overall pick’s days in Cleveland are numbered, it’s clear he’s still training to be a starting quarterback in the NFL. “One last interesting point that I’m hearing is that Baker Mayfield is out in Texas right now working out with Patrick M…