I agree, I feel there should be certain positions that can/can't change to another one. A 300lb linemen should never become a QB. Safeties, CB, & WR shouldn't ever play on the offensive/defensive line. However, there are plenty of WR's who have played QB and vis versa (Edelman, Terrelle Pryor, Braxton Miller, etc.). Or CB's that have played/switched to WR or Safety, D-linemen going to Linebacker, TE used as WR. I don't know what the exact solution should be, but a position change should at the very least make sense imo.
Another idea that might help is if TPE is capped at a lower value for those that changed position to allow for competition down the line and not discourage future prospects. Maybe like a 600 TPE cap or something, since these types of situations should be temporary. Then, when the team has their replacement in line, this player can switch back to their original position and use their full amount of TPE. I feel like this would be enough to not cripple a team, but also allow new players a chance to take the helm sooner. Less of a 'barrier to entry', if you will.
Another idea that might help is if TPE is capped at a lower value for those that changed position to allow for competition down the line and not discourage future prospects. Maybe like a 600 TPE cap or something, since these types of situations should be temporary. Then, when the team has their replacement in line, this player can switch back to their original position and use their full amount of TPE. I feel like this would be enough to not cripple a team, but also allow new players a chance to take the helm sooner. Less of a 'barrier to entry', if you will.