I'm not sure where you got that a player called up to the 55 man roster has to be a lineman but there are no position rules like that.
.
.
It appears the offensive lineman clause concerns the active roster not the 55:
Earlier this week, during our
53-man roster projection, there was some confusion about roster sizes, game day active rosters, the practice squad size, and the game-day inactive list. So I’ll cite some of the CBA changes and do my best to clear up any confusion. Let’s start with the game day active roster. Here is the CBA’s language:
Beginning with the 2020 regular season, the Active List limit shall be increased from forty-six players per Club to forty-eight players per Club; provided, however, that such a Club’s Active List includes a minimum of eight players whose primary playing position is Center, Guard or Tackle (collectively, “Offensive Lineman”).
Interpretation: As long as the team has eight or more linemen that are active, they’re allowed to have 48 roster spots instead of 46, which was the maximum number of active gameday players under the previous CBA. Teams need to have eight players for the five offensive line positions: LT, LGG, C, RG, and RT. If a team doesn’t have the minimum of eight linemen active, will they go back to 46 active players? Here is the CBA’s explanation:
For the sake of clarity and avoidance of doubt,
for any game for which a Club’s Active List includes fewer than eight Offensive Linemen, such Club’s Active List limit shall be forty-seven players. The Clubs may not reduce these limits for the duration of this Agreement; provided, however, that individual Clubs may carry fewer than forty-eight players on their Active List during the regular season or postseason, but
no fewer than forty-four players.
The minimum number of active players is 44, according to the CBA. I doubt any team will willingly field fewer than 46 healthy players. I’d love to know how the CBA arrived at these specific numbers. Also, what their explanation behind having inactive players on the roster is.