One thing I have noticed over the years is that more players seem to end up on I.R. in the final few weeks of the regular season than earlier in the season.   Probably the two reasons for this are with the season coming to an end,   there's less time for players to recover in time from their respective injuries.   And it also gives a team the opportunity to promote players from the Practice Squad or sign players from other NFL Practice Squads.   This in essence ensures that the team will have the rights to the player for the following season unless they are released at some point.

 

By the middle of the regular season,   not counting players that were placed on Injured Waivers in the summer and eventually landed on I.R.,  my guess is somewhere near an average of 6 players placed on Injured Reserve is the number.   

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