Pats were always bringing another QB this offseason. In another Covid preseason 4 is the minimum.
Hoyer acted more as a personal assistant to Tom for some time already and had a lot of trust from both TB and McD.
So he can serve not only to Mac but Cam as well.
Last year Pats had 4 QBs - 3 on 53 and 1 on PS. All teams will cary at least 4 QBs again this year on their combined 53+PS rosters - with COVID protocol likely to remain. In addition: Pats carried 4 QBs on 53 when they drafted Tom.
That wont be necessary now since by current rules they can place anyone on PS and they can protect up to 4 players from being signed by other teams (so in theory they could even put Cam on PS). Here are the PS rules:
The NFL expanded practice squads and introduced new rules due to the pandemic.
theramswire.usatoday.com
btw - These extraordinary PS rules could be one of the reasons why Pats went for vet min vets rather than bringing in UDFAs since they can safely stash some solid vets on PS and use weekly promotions to 53 if needed.
Having Hoyer on the team (rather than coaching staff) has therefore many benefits and zero downside. That is why this move was actually expected (from Pats perspective if Hoyer agreed). He can be used in both depth/extra hand player role and mentor/coaching assistant at the same time. It also gives Pats leverage regarding roster spots and trades. If they want to keep just 2QBs on 53 Hoyer is much better proposition for PS than Stidham who still believes he has some future in the league and still has some trade value esp. in another Covid yr. Hoyer is also better option for 3rd QB on the 53 if they should want to use him in in-game assistant/mentor role.
This move of course says absolutely nothing about who is starting week 1 (except that its probably not Stidham)