Patriots quarterback Mac Jones, left, makes a throw in front of offensive coordinator Bill O’Brien during a practice in June. Steven Senne/Associated Press

Bill O’Brien can joke about what he’s been through in the 12 years since his last tenure as Patriots offensive coordinator.

“A lot of water under my bridge,” O’Brien said, smiling Friday during a video conference call about his time served as head coach at Penn State and for the Houston Texans, and as Alabama’s offensive coordinator.

Tom Brady, Brian Hoyer and Ryan Mallett were the quarterbacks the last time O’Brien was offensive coordinator in New England.

Now leading Mac Jones, Bailey Zappe and Trace McSorely in his return to New England, O’Brien says this is “one of the better quarterback rooms I’ve ever been a part of.”

And it sounds like coaching Jones is a big part of that. O’Brien said his working relationship with Jones is “really good.”

“Mac’s done a really good job,” O’Brien said. “He’s worked extremely hard. I’ve really, really enjoyed coaching him.”

What O’Brien wouldn’t explicitly state is that Jones will be the Patriots’ starting quarterback when the season begins Sept. 10 against the Philadelphia Eagles.

Head Coach Bill Belichick won’t say it either, but in watching practice, it’s obvious that Jones is viewed as the Patriots’ top QB. There has been no semblance of a quarterback competition so far in training camp.

“This is something that is very, very important about our system, our organization, our football team, is that it’s always about performance. It’s about consistent high-level performance,” O’Brien said. “Certainly Mac gets most of the reps with the 1s. You are at practice, you see that.

“But we have a lot of different guys rotating in and out of that lineup. Bailey gets most of the reps with the 2s, you see that. But again, it’s really about consistent, daily performance.”

The Patriots are still making Jones earn his starting role, and so far, he’s doing just that.

The entire offense got off to a slow start early in training camp due to some extenuating circumstances. The team is running a new system, most of the reps were within strict confines of the red zone, and the defense is returning almost every key player from last season.

But the offense has made major strides under O’Brien over the last week-plus, and Jones’ performance has led the way. He had his best practice of the summer on Wednesday and kept his hot streak alive Thursday with more impressive throws. He’s playing with the 1s because he’s outperforming Zappe and McSorely.

O’Brien said the team has confidence in Jones and all of the quarterbacks.

“We have a lot of trust in Mac,” O’Brien said. “Mac puts a lot of time in. Mac’s very prepared every day. We have a lot of trust in Bailey. We have a lot of trust in Trace.”

Jones has enjoyed working with O’Brien, as well. The third-year pro kept talking Thursday about how much fun he’s having in practice. He likes how O’Brien explains the “why” of the play. He said he’s able to play fast within the Patriots’ new offense.

“Mac’s worked really hard since the day I got here and it’s been fun to coach him,” O’Brien said.