Photo by Ezra Shaw/Getty Images

SANTA CLARA – Much has been made of the 49ers’ pair of preseason games and series of training camp practices; a period of time and displays which serve largely to identify who’s in a genuine competition for the final spots on the roster, and who is healthy. But Saturday, when the 49ers play the Kansas City Chiefs at Arrowhead Stadium, will be the best, fairly valid look at the first team before the regular season kicks off.

While some key players will still remain out (see below), it will mark the first time the 49ers can get extended reps for their starters, and identify strengths and weaknesses more accurately before Week 1 at the Tampa Bay Buccaneers.

Garoppolo moving on from rough week with plenty of reps to come

It’s been repeated on a seemingly endless loop, but yes, Jimmy Garoppolo had a pretty rough week last week, throwing five-straight interceptions in practice on Wednesday before going 1-for-6 with an INT and no yards in his first game back since tearing his ACL on Monday. While it was the preseason (the perfect time for issues like those to present themselves), Garoppolo struggled more from a mental aspect than physically, part of the cause for concern.

As Kyle Shanahan said on Tuesday, the interception he threw was a play in which he should have either thrown the ball away or taken the sack. The reason he was actually rushed so freely by Bradley Chubb was his own fault in miscommunicating protections before the snap, as Shanahan said Thursday.

“The miscommunication on the protections that starts usually with the quarterback, changing the protection, you’ve got to make sure everyone gets it,” Shanahan said. “Then, when we don’t have guys blocked because of miscommunication, that you don’t throw it to their team. Worst case scenario you just go down and take a sack.”

Garoppolo will have a full extended look on Saturday, as Shanahan said he would look to get Garoppolo a full half (could be, although unlikely to be more; depends on what the snap count is, which is the determining factor). Garoppolo said he wasn’t happy with his performance on Monday, but recognized there’s a point when dwelling on the past has a negative utility.

“I’m very hard on myself, especially that night watching the film, the next day watching the film,” Garoppolo said. “At some point, you have to move on. You’re still trying to correct those mistakes and not make the same mistakes twice, but if you just dwell on the past and dwell on that one game, you’re going to get stuck there and you will have no success going forward. I think it’s good to be hard on yourself, but at some point, you’ve got to move forward.”

While, in an ideal world, Shanahan would be able to get Garoppolo more than just a half, the need to protect the starting offensive line makes that task unachievable.

“From a quarterback standpoint, it’d be great for Jimmy to leave him in all games and let him do this and go through reps,” Shanahan said. “I want Jimmy to play as much as possible in the preseason and into the regular season, but that’s a fine line too. [T] Joe Staley’s not in the same situation and neither is [T Mike] McGlinchey, right now our whole O-Line. You don’t want to put your quarterback in there versus a starting defensive line when you don’t have your starting O-Line in there. So, trying to balance that out.”

Time for debuts… and also not

Below is a list of players who are expected to make their preseason debuts for the 49ers on Saturday, as well as how long of a run they’re expected to get (if that has been revealed):

Fred Warner – Warner, like DeForest Buckner, has basically had no need to play. The 49ers’ linebacking linchpin has been healthy and the team would like to keep it that way.

DeForest Buckner – His status is the same as Warner’s. He’s expecting to play the entire first half.

Kwon Alexander – Alexander tore his ACL in the Buccaneers’ sixth game of the season against the Cleveland Browns on October 21 last year. Saturday will be the first time he gets back on the field. Don’t expect him to play the entire first half. Alexander said yesterday his return to the field is significant for him: “It’s a big thing for me,” Alexander said. “I ain’t played in a minute, now, so I’m happy to be back out there.”

Jimmie Ward – Ward will play his first game since going on the injured reserve with a broken forearm after playing the Buccaneers November 25 last season. He fractured his collarbone in OTAs and practiced in contact drills for the first time on Thursday. He’s likely trailing Tarvarius Moore in the starting free safety competition solely due to his lack of health, but if he outperforms Moore, he could likely win back the spot.

*Mike Person – Person’s been dealing with a foot injury and practiced on Thursday, an indication that he’ll likely play on Saturday, although that has yet to be confirmed explicitly. If he does play, don’t be surprised if he plays fewer snaps than Staley, McGlinchey and Laken Tomlinson.

*Joshua Garnett – Garnett is not confirmed to play. Head coach Kyle Shanahan said Garnett would practice Thursday (practice for the first time Wednesday, but the first time in pads with contact – while wearing a hand cast – on Thursday) and the team would evaluate whether he’ll play Saturday afterwards, but that he is hoping Garnett can play.

Below is a list of players who are not expected to make their preseason debuts for the 49ers on Saturday:

George Kittle – He as a calf injury, caught a few passes in non-contact team drills on Thursday, although Shanahan said he wouldn’t practice; he may have been indicating he wouldn’t practice in contact drills. Shanahan didn’t completely rule Kittle out of Saturday, but said: “With him not practicing today I would be surprised if he does [play Saturday]. I haven’t decided that yet, though.”

Dee Ford – There was some initial hope that Ford would be able to practice that week, but with the short turnaround from Denver to Kansas City, Shanahan nipped that in the bud earlier this week. Ford was out (not in uniform) throwing the ball around before practice, and is expected to get back into practice next week.

Nick Bosa, Jason Verrett, Weston Richburg, Jerick McKinnon, Garrett Celek – This group won’t play in the preseason

Other injuries, notes

• Out of Thursday’s practice were Adrian Colbert (hamstring), Jullian Taylor (back stiffness), Tim Harris Jr. (groin) Elijah Lee (surgery on his thumb)
• Jordan Matthews has been taking few snaps because the 49ers know what they’re getting with him, Shanahan said Thursday. Shanahan gave Matthews a vote of confidence, although it’s hard to read too much into compliments before the roster is cut down to the final 53, considering the potential for trades (see, when Shanahan complimented C.J. Beathard as being a constant big play threat on Tuesday). Still, it won’t be surprising if Matthews makes the roster. Here’s what Shanahan said about Matthews’ limited snap count Thursday:

“That’s an indication that we feel very good about we know what Jordan is. Jordan’s had a hell of a camp. He’s done very good in practice, he’s been consistent in OTAs, he’s been very consistent in training camp and we’ve seen him a lot on tape before he got here. I’ve got a lot of confidence in Jordan and I know we can win with Jordan. Trying to find out a little bit more about other guys that we don’t know as well and you’ve got to give those guys that opportunity. I did wish he played a little bit more versus Denver. We were going to have him go in at F and then switch in later with [WR Jalen] Hurd, and then Hurd ended up having back tightness, we ended up giving [WR] Richie [James Jr.] those opportunities. That says nothing about Jordan. We know what Jordan can do and we’re trying to find out what more of these other guys can do.”

• The numbers game means that Shanahan and Lynch are going to have a tough time cutting the roster down to 53, much more so than in previous years. Shanahan left the door open for three quarterbacks to make the roster, as is his ideal (he says he doesn’t want to cut Beathard or Nick Mullens) situation. Here’s what Shanahan said on the impending difficulty of cutdowns:

“This is different than every other year where we’ve had to where getting down to this final 53 is going to be a lot more stressful for [general manager] John [Lynch] and I than it has in the past. Usually, you’re excited to do it a little bit more, because we already know who it is and we’re hoping, we think there’s five guys on someone else’s roster that can add to our 53. We know we have more than 53 players now and we’ve also got a lot of guys out, too. But, they’re guys that we think are going to return here in the first couple of weeks. So, that makes them very tough decisions on the final three, the first day is 46 and there’s going to be a player that we want to keep without a doubt that won’t be able to be on our team this year. It’s tough, it’s stressful, but that was our goal. I’m glad that we’re here at this point and hopefully that continues.”