While browsing through players, you may see that a plyer is "High Motor". You may wonder what that means! Let me break it down for you. In my opinion, this trait is incredibly important. It afects your player in many ways that just enhances their level of peformance on the playing field!
Better Stamina - Players that are "High Motor", will lose stamina at a slightly reduced rate. Most importantly, when they are at low stamina, they will still play at better standards than other players who are not high motor. For example, a WR with "High Motor", may only run 4 speed slower while at 60% stamina while a player without it may run at 6 speed slower(JUST AN EXAMPLE). Therefore, having this trait allows your players to not be affected as severly as others by fatigue!
Improved Effort - High Motor players play much better as well. They tend to hold their blocks much longer on offense. On defense, they seem to get back up if pancaked to make plays, and try to chase players down more often. High motor players just seem to last longer out on the field and "wear out" much slower.
These are just observations made my members of the community along with some I have made. Nothing here is official per EA, but I see a lot of it with my "High Motor" players! I do not think you should select players based on traits all the time, but it is a great trait to have!
