Interesting notion but I think there might be a little more to it... I think when you make a switch for a few DAYS you are doing more than just teaching... I don't think you sacrifice valuable reps just to coach somebody to be a backup or add versatility... It's kind of like taking Incognito out of the lineup to learn to be a long snapper...
Chemistry is CRUCIAL.. Coaches know it... They need to play together... Learn each other's nuances and tendencies... Truthfully I think Coyle is the new guy and he comes in here without any preconceived notions of what a player is or isn't... I think he wants to see for himself who fits where... So I think it really is more of an audition than your post suggests... With the added side benefit of motivating Davis...
I have no doubt Davis will be back in that spot but that is because he is better than Marshall... Not because he played there before... Sparano was afraid of his players, and coddled the vets... I hope this is a sign of a coaching staff that will play the best guy on Sunday. PERIOD.