SANTA CLARA – Defensive coordinator Jim O’Neil spent the bye week studying and identifying what has gone so terribly wrong with the 49ers’ run defense this season.
After all, the 49ers have surrendered an average of 185.1 yards rushing per game. Each of the 49ers’ opponents during the team’s six-game losing streak has produced a 100-yard rusher against O’Neil’s defense. His conclusion was not exactly ground-breaking.
“We got to tackle better. We got to do a better job getting off blocks,” O’Neil said on Tuesday, the 49ers’ first day back after a seven-day vacation for the bye week. “If there were two things that jumped out off the tape, those would probably be the two biggest things.”
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It all starts up front, and that might be the greatest cause of concern for the 49ers. General manager Trent Baalke invested the team’s top draft pick the past two seasons on similar defensive linemen.
Arik Armstead is listed at 6 foot 7, 292 pounds. He was the 49ers’ first-round pick in 2015. DeForest Bucker is 6-7, 300. He was the No. 7 overall pick this year. Coach Chip Kelly recruited both players to Oregon.
But while Armstead and Buckner have shown flashes of their athleticism and the reason they were first-round draft picks, they have not been stout in the run game at holding the point of attack.
“I don’t think the height thing has much to do with it,” O’Neil said. “Actually, the more length you have as a player, the easier it is to escape blocks. It gives you more space between you and the blocker.
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“(But) you learn if your pads get up in this league, you’re going to get knocked off the ball.”
Buckner played a season-high 97 percent of the 49ers’ defensive snaps in the team’s 34-17 loss to the Tampa Bay Buccaneers before the bye week. Buckner got pushed around, as the Buccaneers gained 249 rushing yards with a 6.1 average. Armstead play time has been limited due to a shoulder condition that might require offseason surgery, he said.
“It’s not like their pads are high all the time,” O’Neil said. “As the game goes on and the plays start to mount, as you get tired, the tendency might be to pop up a little bit. It happened a couple of times in the last game and they got knocked off the ball as a result of it. Those guys will learn from those plays and they’ll do better next week.
“Some of those guys are so big, so strong, they’re so athletic, they’re such good football players, there’s stuff they can get away with at the college level. But now you’re in the NFL and you’re playing against grown men who’ve been in the league for 8, 9, 10 years who understand pad level. It’s part of the learning curve.”
The 49ers are having breakdowns at every level, though.
They’ve struggled along the defensive line. The team’s inside linebackers – minus NaVorro Bowwman and Ray-Ray Armstrong – are scuffling with Nick Bellore, Gerald Hodges and Michael Wilhoite. And the tackling in the secondary has not been sharp, either.
The 49ers have surrendered 32 run plays of more than 10 yards in the past six games, including 11 runs of 20 yards or more.
“If it was just one guy, that guy wouldn’t be playing,” O’Neil said. “We just have to tighten everything up as a group.
“They types of plays that cause 44-yard runs is an outside ‘backer running up field, an inside ‘backer not reading his key, and a DB missing a tackle. That’s what causes 44-yard runs.”