Brock Purdy’s record-setting day vs. Cardinals more impressive with context –

Brock Purdy set a 49ers franchise record Sunday for single-game completion percentage with the fourth-best mark by a quarterback in NFL history.

And that’s not all.

Purdy’s completion percentage of 95.2 percent against the Arizona Cardinals was a whopping 28 percent over expected, according to Zebra Technology’s on-field tracking.

That figure points to the fact that Purdy did not pad his accuracy numbers with a bunch of high-percentage throws.

Purdy’s day provided the highest completion-percentage-over-expected mark for any quarterback with at least 20 pass attempts in a game over at least the past seven NFL seasons.

Purdy completed 20 of 21 pass attempts for 283 yards with one touchdown, no interceptions and a passer rating of 134.6 in the 49ers’ 35-16 victory over the Cardinals.

Coach Kyle Shanahan this week had difficulty answering a question about whether Purdy has shown noticeable improvements in the mechanics of running the system. Shanahan said Purdy started off at such a high level after he moved into the starting lineup last season.

“He has [improved], but he was real good in those last year too,” Shanahan said. “He came in right away and didn’t make much mistakes on that stuff.”

On Sunday, Purdy had the longest pass completion in air distance traveled in his career with a throw that traveled 46.8 yards, which Brandon Aiyuk caught for a 42-yard gain. That play had a 27.8-percent probability of being a completion, according to Zebra Technologies.

Purdy’s previous best completion percentage over expected for a game was 5.1 percent.

He has gotten off to a strong start for the 49ers, who remain as one of just two unbeaten teams in the NFL. The Philadelphia Eagles also are 4-0.

Purdy leads the league with a passer rating of 115.1. He has completed 81 of 112 pass attempts (72.3 percent) for 1,019 yards with five touchdowns and no interceptions.

Shanahan said the way Purdy stepped in last season, prepared to play well on few practice repetitions, made it an easy decision to keep him as the starter as he entered his second year in the NFL.

“That’s why he gave us the confidence in going into this year with him, and he took off right where he left off,” Shanahan said. “Just like everybody, the more you get out there, the more you put yourself through it, all the stressful situations, the more confidence you get, the easier it gets.

“But he was so good at it last year and I feel like he’s stayed the same, if not gotten a little bit better.”

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