"Traditionally", we carry 5 interior linemen and 3-4 OT's. This MUST include a backup center.
Obviously if Mankins ain't ready to start the season, we will need an additional player.
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WIT MANKINS READY FOR GAME ONE
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OG/C LOCKS: Mankins, Connolly, Waters, Gallery, center (could be backup center)
OT LOCKS: Solder, Vollmer, Cannon
CENTER
We have Koppen, Wendell and MacDonald competing for the center/backup center roster spot. I don't think any of us would like to see any of these three starting at guard this year.
THE 9th ROSTER SPOT (IF THERE IS ONE)
For me, one issue is backup OT. I guess all three of our OT's can play both LT and RT. Otherwise, we need another OT on the 53 man roster (as is often the case). My "guess" is that Gallery is expected to be able to be our RT if we have 2 injuries at OT. If this is the case, we don't need a 4th OT (we would need to have an developmental LT on the Practice Squad).
Presuming that Connolly is starting at center, we need a backup OG (Gallery) and a backup center (Koppen or Wendell or MacDonald).
We could carry a 9th OL, as a developmental player or emergency backup. The presumption would be that the team didn't want to risk having this player on the Practice Squad, if this is an option at all. Given the injuries to Vollmer and Mankins, I could see us carrying the additional OL. For me, 9 is the "norm" in any case, and I am happy enough counting Gallery as the 4th OT instead adding a player for that the 4th OT "roster spot" and freeing up a roster spot for another player (perhaps MacDonald).
BOTTOM LINE
We will have 4 competitors at center, with Connolly the only player to have a lock on his roster spot (since he can start and backup all the interior OL positions). Other than Connolly, I believe that the other 3 should be considered "pure" centers, at least for 2012.
There could be a 9th OL roster spot because of the position flexibility of Connolly and Gallery (and perhaps also of Cannon). This 9th OL roster spot could be filled by several players (including someone not here yet; for example a vet backup LT). It also could be a position that is filled by committee depending on injuries during the year.
AN ASIDE
I suspect that if Koppen cannot win the starting job at center, he may still make the roster, perhaps in addition to MacDonald or Wendell. Connolly and Gallery can both start at 3 positions. If there are injuries, it the center position that needs have the most depth, since the backup centers have little position flexibility.
This gives us a very solid 8 man roster, with the option of carrying a 9th OL.
C Connolly/Koppen
OG Mankins, Waters
interior starting quality backups: Connolly/Koppen, Gallery
OT Solder, Vollmer, Cannon