Grant Cohn: What to watch for in 49ers' 3rd preseason game

Before training camp, the 49ers seemed on the verge of a nine-win season. Maybe 10 wins.

Now, seven. Max.

Training camp was a bust. Eight starters injured themselves and lots of backups did, too. The 49ers are limping into the regular-season opener.

Saturday is the preseason dress rehearsal against the Indianapolis Colts. Starters will play the entire first half. Most of the injured starters will play, too. That's the plan. If the 49ers seem rusty and unprepared, they could lose each of their first-four regular season games. The schedule is that tough. This game means something.

Of course, it's still the preseason, not necessarily a predictor of the regular season. The 49ers have not looked good in the first two games, making this game very important.

Here's who and what to watch for during Saturday's dress rehearsal.

1. Richard Sherman.

Head coach Kyle Shanahan said Sherman will play every snap with the starters. Sherman is a 30-year-old cornerback who tore his Achilles nine months ago, played no more than three snaps in a row during training camp and still pulled his hamstring on just his sixth day.

That was three weeks ago. Now, Sherman wants to play the whole first half and show he's fully ready for the season opener two weeks from Sunday.

The Colts should show us what we need to know about Sherman. Even if they don't throw his way — and I expect they will — they'll test Sherman by making him run.

How many deep routes can he cover before he pulls his hamstring again? Is he really ready to play full time?

If he's not, the 49ers pass defense will continue to rank among the league's worst.

2. Pass rush.

Sherman can't succeed without one. In his prime years in Seattle, he always had the benefit of a terrific four-man pass rush.

Like the Seahawks, the 49ers' defense relies on a four-man rush. It rarely blitzes. Most of the time, defensive coordinator Robert Saleh uses Cover 3, which features seven players in coverage and the remaining four rushing the quarterback.

Last season, the 49ers four-man rush was bad. The defense recorded only 30 sacks, which ranked tied for sixth fewest in the league. Remarkably, the team took zero edge rushers in this year's draft, and chose not to re-sign the team's sack leader from 2017, Elvis Dumervil.

Instead, the team hired coach Chris Kiffin, a pass-rushing specialist, hoping he will fix everything. He's supposed to manufacture a four-man rush with the same players who struggled to produce last season.

So far, Kiffin has manufactured nothing. The starting defense has sacked opposing quarterbacks just once through two preseason games. Quarterbacks look like beach bums relaxing at Stinson when they stand in the pocket against the Niners. Dak Prescott and Deshaun Watson — the two starting QBs who faced the Niners so far this preseason — have a composite quarterback rating of 144.7 against them.

Now, they'll face Andrew Luck. Then, Kirk Cousins Week 1. Then Matthew Stafford. Then Patrick Mahomes. Then Philip Rivers. The Niners better find a way to hit them.

3. Run defense.

This supposedly is the strength of the defense. Last season, the 49ers allowed only 3.8 yards per carry, which ranked seventh lowest in the NFL.

In the preseason, the starting defense has allowed 4.4 yards per carry. And on Thursday, the 49ers traded one of their better run defenders – strong-side linebacker Eli Harold.

They replaced him with Mark Nzeocha, who is smaller and faster than Harold. Nzeocha's skillset suggests he will be an upgrade over Harold in a pass coverage, but not as a run defender.

The Colts will try to run over Nzeocha. Watch how he performs at the point of attack.

4. Right guard.

Who will start at this position?

In the first two preseason games, Mike Person started at right guard because Joshua Garnett and Jonathan Cooper missed time with injuries during training camp. Person is a serviceable backup who should not start. If he plays with the starters on Saturday, that's a problem.

The 49ers need Garnett or Cooper to start, play well and take ownership of this position. Otherwise, right guard will be a major weakness defenses will try to exploit during the regular season.

5. Run blocking.

The first-string offense has rushed for nine yards on 12 carries during the preseason.

Granted, Jerick McKinnon and Matt Breida, the top two running backs, suffered injuries during the preseason opener and missed the second game. But, the running backs aren't the issue.

Blocking is, from the offensive line to the tight ends to the fullback. They have created no holes, so the 49ers have had to pass. Jimmy Garoppolo has accounted for 95 percent of the offense.

That's dangerously high. A running game protects the quarterback. If the 49ers have no run game, Garoppolo will throw too much, get hit too much and expose himself to injury. Not what the Niners want.

But the future is entirely open to them. They can be the team people expect them to be. It's up to them.

Let's see them run and block and sack and cover effectively Saturday. Let's see they're more than a mere seven-win team.

Grant Cohn covers the 49ers and Bay Area sports for The Santa Rosa Press Democrat and pressdemocrat.com. You can reach him at grantcohn@gmail.com.