Tony Fiammetta became the latest fullback to join the Patriots. (AP)

The Patriots have already added one fullback this offseason in Spencer Larsen, and on Monday, they reportedly agreed to a deal with Tony Fiammetta. They already have one on the roster in Lousaka Polite, and could have a fourth in Eric Kettani, who was recently activated off the reserve/military list.

So what’s with all the fullbacks?

In the Bill Belichick era, the Patriots have occasionally employed a regular fullback, but they’ve never had this many on the roster at one time. Polite, who signed at the end of the regular season, was the first regular fullback New England utilized since Heath Evans departed following the 2008 season. (Patrick Pass had the longest career of any fullback with the Patriots under Belichick, playing in New England from 2000 until 2006.)

If you’re putting together a depth chart at this point, Polite is probably the No. 1 back, based on talent level and basic knowledge of the system. He’d be followed by Larsen, who also has extensive special teams value (as well as on defense). Fiammetta is still an unknown quantity at this point, but on paper, appears to be more of a traditional blocking fullback. Kettani remains a question mark — he’s been around the franchise since he was signed as an undrafted free agent in 2009, but has little on-field action.

Some of it could be due to the fact that the Patriots have lost veteran back BenJarvus Green-Ellis in free agency, with the understanding that the two young running backs — Steven Ridley and Shane Vereen — might fare better with a lead blocker in front of them. It’s a theory that analyst Sam Monson of Pro Football Focus agrees with.

“If I was guessing, I’d say they want to use more of a fullback next season,” Monson wrote in an e-mail to WEEI.com, “perhaps figuring the current running back stable would run better with a lead-blocker than BenJarvus Green-Ellis, and are loading up on guys to pick from when they get into the analysis of the roster.”