3 early differences between 49ers QBs Mac Jones and Brock Purdy

These stats tell the story.

San Francisco 49ers quarterback Mac Jones. | Stephen Lew-Imagn Images

While it is much too small of a sample size to make sweeping proclamations, there is enough of a sample size between Mac Jones and Brock Purdy this season to see how they operated the San Francisco 49ers quarterback position differently. What were the biggest changes?

Brock Purdy had boom and bust, Mac Jones was steady 

While Brock Purdy averaged more yards per attempt than Mac Jones, Mac Jones had a higher adjusted yards per attempt, which factors in interceptions. He also had a higher adjusted net yards per attempt, which includes sacks. 

Brock Purdy had a little more boom, but he also brought more bust. His two interceptions were back-breakers and bad decisions. Pro Football Focus graded him with a 4.8% turnover-worthy play rate. Mac Jones was not perfect, but he posted a 2.2% turnover-worthy play rate, showing a steadier hand. 

Jones had three touchdowns, but his came more through playing within the offense and hitting the open man. Brock Purdy was hitting more high-leverage passes that were flipping the field, or turning low-probability outcomes into high ones. Purdy had a 7.9% big-time throw rate while Jones was at 0. 

Stephen Lew-Imagn Images

Mac Jones took too many sacks

Mac Jones took three sacks in this game. Even worse, he did not face a lot of pressure, and when he was sacked, it was because he held the ball for far too long. He had a 37.5% pressure-to-sack rate. Only Tua Tagovailoa and JJ McCarthy are worse so far this season. Brock Purdy is down at 5.9%

Yes, Purdy had his interceptions, and statistically, those were worse than the sacks for Jones. At the same time, Purdy had three scrambles, while Mac Jones just had one. There were a few more times where Jones may have been able to create, but did not. 

Stephen Lew-Imagn Images

Mac Jones faced a softer defense

The other question to take away from Jones and all of the sacks he took is that he faced a softer defense. Jones was under pressure on just 18.6% of his drop-backs, while Purdy was under pressure on 43.6% of his drop-backs. Christian McCaffrey averaged 3.1 yards per carry against Seattle and 4.2 against New Orleans. 

It would have been tougher for Jones to operate against Seattle in the same manner. It may have worked out that they needed a splash play here and there to beat a tough Seattle group, but against New Orleans, they just needed someone to keep the train on the tracks.