Jabaal Sheard doesn’t travel to San Francisco

Jabaal Sheard has recorded just half a sack over his last five games.Matthew J. Lee/Globe Staff/File 2016/Globe Staff

SAN FRANCISCO — The Patriots traveled to the Bay Area on Friday in advance of Sunday’s game against the 49ers, but defensive end Jabaal Sheard didn’t join them.

Sheard, who has 3½ sacks in nine games, was not on this week’s injury report and was left back in New England per a team decision. While his teammates were landing Friday night in San Francisco, Sheard posted to his Instagram account a video from the stands at the Celtics-Warriors game at TD Garden.

The reasons for Sheard being left behind are unclear. But after playing in 70 percent of the team’s defensive snaps through the first eight games — and no fewer than 35 snaps in any game — Sheard played just 16 snaps in last Sunday’s loss to the Seahawks, the Patriots’ first game back from their bye week.

Coach Bill Belichick was a bit evasive Tuesday when asked about Sheard’s reduction in playing time.

“That’s the kind of question that I get every week,” Belichick said. “If one player’s numbers are a little bit higher and then others’ are a little bit lower, it’s basically the same question that you just asked, but change the players’ names around and it’s a weekly question.

“To a point, play time is based on performance, but it’s also affected by situations and the type of game and type of matchups that that particular game, that are particular to the characteristics of that game . . . In the end, we play the players that we feel like will give us the best opportunity in any given situation in a particular game, or the way that that game happens to unfold based on what our opponents are doing and how the game situations play out.”

Sheard, 27, is in the final year of a two-year, $11 million deal. His first season in New England went well, finishing with eight sacks and four forced fumbles in 13 games. But Sheard’s production has slipped this year — only a half-sack over his last five games, and no forced fumbles or impact plays this year.

Second-year pro Trey Flowers played 61 snaps in Sheard’s place last week against the Seahawks and finished with two sacks. Veterans Rob Ninkovich (46 snaps) and Chris Long (37) also played significant roles at defensive end.

The Patriots are required to officially downgrade by Saturday night any player that didn’t make the trip west. They have already ruled out tight end Rob Gronkowski (chest) and receiver Chris Hogan (back). But running back Dion Lewis, activated last Saturday to the 53-man roster, made the trip to San Francisco, per the Patriots’ Twitter account.

Rowe wants in

One of last Sunday’s surprises was that cornerback Eric Rowe was made inactive after starting games in Pittsburgh and Buffalo. Rowe said Wednesday that he was shocked by the decision, which he learned of just hours before the game.

Rowe hadn’t seen it coming — he expected to play and said last week that he was hoping to start — but he wasn’t angry over the decision. He did say it was frustrating to watch the team struggle defensively from up in the box.

“That last fourth-and-1 play I was like, ‘Damn, I want to be out there,’ ” Rowe said.

The Patriots are deep at cornerback, where Malcolm Butler and Logan Ryan started against Seattle. The team carries all six of its corners on the 53-man roster, and at least one has been inactive every game this season.

Rowe called it a “friendly competition” and acknowledged that it’s a good thing the Patriots have a lot of talented players.

“Jeez. Six DBs! With the Eagles we only had like three,” Rowe said.

Analyze that

Belichick doesn’t care about your fancy advanced stats. The Patriots coach was asked Friday about how Tom Brady’s quick release factored into the offense, and if it’s become more important lately as more and more websites have tracked similar metrics.

“The what now?” Belichick asked.

“What is that? I mean, you could take those advanced websites and metric them — whatever you want. I don’t know. I have no idea. I’ve never looked at one. I don’t even care to look at one. I don’t care what they say. As far as a quarterback goes, read the coverage, throw the ball to the open receiver, and take the best matchup.”

Aside from being generally cranky, Belichick’s main point was that boiling release time down to a number doesn’t capture the full picture of a throw, where coverage and receivers getting open affect timing.

“If we don’t have anybody open, who is the quarterback going to throw it to? It’s timing, decision-making, execution by the entire offensive team,” Belichick said.

Belichick tacked a zinger on at the end: “You’d need to ask that to a smarter coach than me,” he said.

Backup plan

Belichick offered some unprompted high praise for Jimmy Garoppolo in response to a question about Brady’s dependability. After saying how having Brady consistently available helps the rest of the team make the most of practice reps, Belichick added that Garoppolo is an excellent understudy.

“Jimmy can go out there and run everything that Tom can run. We’ve seen that, so I’m not saying that he’s not capable or qualified to do it. He is, and he does a great job of it and when we put Jimmy in there it’s really seamless,” Belichick said. “Unless you were actually looking at the position, if you just could block out that position and say which guy was in there at quarterback, I don’t know if you would know a lot of times.”

Combo platter

The pressure is on Flowers and the rest of the Patriots’ front seven to bring the, well, pressure Sunday. Flowers was a bright spot with two sacks against Seattle, but the defense will be better served by making Colin Kaepernick consistently rushed and uncomfortable.

Having pressure and coverage working in concert is more important to the Patriots than having select players blow by their matchups.

“It’s all in one,” Flowers said. “I could have a good rush but then if the secondary leaves somebody open, me, I just think it’s a whole team thing.”

On right path

Fullback James Develin, who has contributed a number of key blocks this season (including one last Sunday that opened an outside lane for LeGarrette Blount to score a touchdown), credited the offensive line for the Patriots’ success this season. “I mean, our offensive line has been doing a great job, they’ve really been paving the path and our backs have been running really hard,” Develin said. “[Blount] is a dangerous weapon, he’s got a little bit of everything and if we can get him going it’s really fun to watch him go.” Develin has played in each game this season, but has yet to carry the ball. In parts of four seasons, Develin has seven career carries for 15 yards and one TD . . . In order to leave around 2 p.m. for California, the Patriots had media availability at 6:45 a.m. Friday. What’s the best way to wake up for an early morning practice? “Bright lights and cameras in your face,” Flowers said.