It’s difficult to register just how big the loss of Shaun Hill is to the Lions. Hill, Matthew Stafford’s backup the past four seasons, signed a one-year deal with the St. Louis Rams.

He’ll be closer to his offseason home and he’ll have a good chance to learn the Rams system during OTAs since starter Sam Bradford is recovering from a torn ACL. He’ll reportedly earn $1.75 million with a chance for $2.25 million.

The 34-year-old Hill is considered one of the NFL’s best backup quarterbacks. It’s not because he’s good at carrying a clipboard.

Hill helped Stafford make the adjustment to the NFL. Daunte Culpepper was the backup Stafford’s rookie season, then the Lions made a trade for Hill prior to the 2010 season.

It wasn’t just in practice that Hill helped mentor Stafford. Through each game. Hill kept his helmet on along the sidelines so he could hear the play calls. Then he’d watch the defense on each play. He’d convey the information to Stafford when he came off the field. Hill may not have played much the past three seasons, but his NFL experience was key.

While his work ethic was unquestioned, he also had a great dry sense of humor and helped to keep the atmosphere light.

The Lions wanted Hill to return, but the one thing they couldn’t offer is a chance to start. Stafford hasn’t missed a game in three seasons while Bradford missed nine in 2013 and six in 2011.

Not many veterans available on the free agent quarterback tree these days.

One is Dan Orlovsky who was with the Lions for four seasons (2005-2008). 

He also started and lost seven games for the Indianapolis Colts in 2011 when Jim Caldwell was the head coach and Peyton Manning missed the season. The Colts went 2-14 and Caldwell lost his job. So he knows Orlovsky.

Also, general manager Martin Mayhew said the Lions could draft a quarterback in later rounds and use him or Kellen Moore as the No. 2 backup this season.

Moore, who was signed as a rookie free agent in 2012, has improved in his two seasons with the Lions but has never played a snap in an NFL regular season game.

Stafford, even at age 26, has five NFL seasons behind him. Not saying he can’t win without a quality veteran backup, but it certainly would be a benefit.

(Follow @PaulaPasche on Twitter. Order her book,  “100 Things Lions Fans Should Know & Do Before They Die’’ here. It’s also available at bookstores.)