One thing keeping Mac Jones from being a legitimate starter for 49ers

This is a serious limitation.

Darren Yamashita-Imagn Images

Mac Jones has been a massive addition to the San Francisco 49ers this offseason. The team is 4-1 when he starts this season, and his play is a big reason why the team is winning. At the same time, the 49ers may be playing to his strengths and getting the most from him. 

Mac Jones is struggling in one area for the San Francisco 49ers

Judah Fortgang put together a chart highlighting expected points added against zone coverage and man coverage for each quarterback. Mac Jones stands out in this chart for his performance so far. 

QB EPA Man & Zone pic.twitter.com/FyT8euSBIl

— Jrfortgang (@throwthedamball) October 24, 2025

The only quarterbacks better against zone coverage this year are Dak Prescott and Patrick Mahomes. That is quite the company to be in. Against man coverage, the only quarterbacks worse are Cam Ward and Joe Flacco. That is poor company to be in. 

Brock Purdy did not have enough of a sample size to appear on this graph, but he currently has a 0.97 EPA/play against man and 0.07 against zone. That would put him right between Kyler Murray and Trevor Lawrence on the chart referenced. 

It is notable, but explainable, why Purdy has been so much better against man coverage. Purdy has been able to play with a top-caliber talent at wide receiver in Ricky Pearsall, while Mac Jones has been dealing with an injured receiver corps. 

Pearsall averages 4.59 yards per route run against man coverage. When Purdy had his man in single coverage, he threw to him with success. It was his easy button.

Darren Yamashita-Imagn Images

The easy button that Mac Jones has is Christian McCaffrey, who has been the top receiver with Pearsall out. McCaffrey will mostly see the soft zone coverages as he gets running back looks. 

Kendrick Bourne also averages 2.22 yards per route run against zone compared to 1.37 against man. This makes sense because Bounre is an older and slower receiver, but he leans on being smart and understanding where to go against certain looks. This is the opposite of Pearsall, who is young, fast, and can beat man coverage. 

Some of this has to do with Mac Jones as well. His physical limitations were always noted coming out of college, and he has shown that he can pick apart defenses that give him zone looks because he is smart and accurate. However, he is not a playmaker. He does not put passes into tight windows or push the ball to spots that only certain players can hit. Jones also does not make the plays out of structure needed to beat man looks. 

Jones has done a great job holding things down, but when healthy, the physical upside and playmaking mentality of Purdy still will give the offense a higher ceiling.