I would have chosen to sh!t-can Myles of Space Bryant and promote Mitchell as soon as I heard that he was being courted...
First, Belichick obviously favored Bryant over Mitchell.
If he was to choose Mitchell, he would have been on the 53. As far as "hearing" that someone else wanted him. the choice was in Mitchell's hands. Perhaps Belichick made an offer, perhaps not.
I suspect that Mitchell would prefer the offer from another team, guaranteeing 3 weeks pay.
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We need to realize that putting a player on the Practice Squad is a choice. It means that the player isn't worth being on the 53, at least in the eyes of the team. There will always be players that fans would choose to be on the 53 instead of the Practive Squad.
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BOTTOM LINE
Belichick chose Bryant over Mitchell, and is likely fine with the choice.
As far as OT is concerns, Belichick has had 2 backups on the 53. I expect that to continue with Cannon replacing Herron.
Finally, there is no one on the Practice Squad that I would prefer being on the 53, other than Cannon.