As a pure WR outside the Shanahan system I think Jauan Jennings is probably a low end 2 high end 3. He does bring other traits like he is an excellent blocker for a WR. As a receiver he is a good route runner and good making catches in traffic and contested catches.
I think the route running point is important because he is a good route runner within structure. He is a competitor and he has clearly mastered the nuances of Kyle Shanahan’s system. He understands spacing, he settles well in zones, and he is where he is supposed to be on time. But a lot of what makes that look clean is the environment he is operating in. In this offense separation is often schemed rather than earned. With motion, bunch formations, and stacked releases defenses are constantly dealing with off coverage, traffic, and communication stress. That leads to free releases, leverage advantages, and zone voids already opening up. So Jennings is not being asked to consistently win against press or create separation with speed, which is not really his game. He ran a 4.74 at his pro day and that was six years ago, he probably has not gotten any faster. It makes his routes look sharper and more effective than they would in a more static offense where he has to generate that separation on his own.
The YAC element also does a lot of the heavy lifting. The offense is built on slants, crossers, and in breaking routes where the ball is coming out in rhythm and into space. Jennings fits that well because he is big, physical, and tough over the middle. He does not need burst or deep speed, he just needs to secure the catch and fight for extra yards. The design creates space first and then asks him to finish, which plays directly into his strengths and boosts his efficiency.
Then you layer in the run game and play action. Because the wide zone system is so effective defenses are stepping up, safeties are coming down, and linebackers hesitate. That opens intermediate windows and crossing routes behind them. Jennings lives in that 8 to 15 yard area. He is not consistently winning deep or stressing defenses vertically, he is catching the ball where the defense is already conflicted.
So you end up with a player who is good at what he does and very useful in that role, but the role itself is not one that typically commands top tier money. He is not dictating coverage, he is not creating explosive plays at a high rate, and he is not someone defenses have to tilt toward. A lot of his production is tied to scheme, spacing, and situation rather than individual matchup wins. That is why it is hard to justify paying him like a primary option at 20 million a year when his value comes more from being a high level complementary piece than a true driver of an offense.
Shanahans system can turn a smart, physical, possession who in other system is probably valued as a low end 2 or 3 into a high end 2 and that is what I think happened with Jennings. Low end 2/high end 3 money is like 10 to 12 million a year, high end money is 20 million a year.