The No. 1 characteristic for any quarterback entering the New England Patriots' system is a high football IQ.
The Patriots put a lot of emphasis on the quarterback to get the offense into the right protection calls. You always see Tom Brady come up and point to a guy on the defense, right? Well, that's a declaration for the offense for who they're blocking on a particular play.
There are a lot of complexities to this offense, so you need a guy with a good football IQ who was brought up in a good system and can comprehend that stuff quickly.
You obviously have to be able to make the throws and have the general physical qualities they look for in terms of being a strong pocket passer. But you also have to be able to manage the other stuff.
That's why Philip Rivers is an intriguing guy, because I still believe he can play at a high level.
He's obviously an outstanding leader and a veteran. But he's also been in a Los Angeles Chargers system with Ken Whisenhunt, who runs a very similar offensive scheme as New England with similar language. So, there's some carryover there.
You're going to pay for Rivers. But if you're looking for a guy to fill a one- to two-year bridge gap, you know what you're getting with him. You know he's a competitor. He can still play and is a great leader on the field.
Bringing in Rivers would also give Jarrett Stidham another opportunity to grow behind a veteran guy who's played at a high level for a long time.
That's a big factor in all of this: How much belief do the Patriots have in Stidham?
If you commit to a guy like Rivers, you're essentially guaranteeing he's going to be on the field because of his contract situation. You're saying, "He's going to be the guy that's playing."
But if the Patriots really believe in Stidham, then maybe they target a younger guy who isn't as expensive, such as Teddy Bridgewater, Marcus Mariota or Ryan Tannehill: guys who have veteran experience, but you're still comfortable playing Stidham if for some reason they don't work out.
If you do bring in one of those guys, they're going to have to compete for a job. With Jarrett being in the system for a year, he's going to be leaps and bounds ahead of a lot of these guys. So, the Patriots are going to let them compete for the starting job.
The veteran may well win that job, but I can absolutely see a scenario where they bring in a veteran guy and let those two guys compete in the offseason.
Even if they have a lot of confidence in Stidham, though, they're still going to want a veteran presence in the room who he can bounce ideas off of: a voice who can help him out.
You never know what you're going to get in the draft, so there should be an element of experience with any free agent they bring in.
Editor's note: Matt Cassel had a 14-year NFL career that included four seasons with the New England Patriots (2005-2008). He's joining the NBC Sports Boston team for this season. You can find him on game days as part of our Pregame Live and Postgame Live coverage, as well as on Tom E. Curran's Patriots Talk podcast and NBCSportsBoston.com.
Matt Cassel: Could Philip Rivers fit as Patriots' 'bridge' quarterback? originally appeared on NBC Sports Boston