We're about to find out a lot about the San Francisco 49ers, Kyle Shanahan and Brock Purdy, even as he is on the sideline.

Purdy went in the NFL's concussion protocol Wednesday and is very unlikely to play Sunday against the Cincinnati Bengals. That means Sam Darnold is in line to start. When that news broke, the line at BetMGM moved from 49ers -5.5 to -3.5.

We're about to get plenty of victory laps from one side of the Purdy debate, depending on how Darnold plays.

For those who believe that Purdy is just a product of the system and Shanahan can take any quarterback to stardom, a big game from Darnold would be their proof. If Darnold struggles, maybe that means Purdy is better than many want to give him credit for. The game will say a lot about Darnold, too. He hasn't worked out as a No. 3 overall pick, but he also has never been in a situation as good as this one.

The 49ers are in a precarious position. Through five games they were undoubtedly the best team in the NFL. Then they lost to the Cleveland Browns, who had P.J. Walker at quarterback, and then to the Minnesota Vikings. San Francisco was a big favorite in both games. Now they are looking at a possible three-game losing streak. Nobody wants to give the Seattle Seahawks much credit, but Seattle could lead the NFC West by Sunday night if the 49ers lose to the Bengals.

The Bengals are coming off a bye week, which gave Joe Burrow and his calf a much-needed week of rest. The Bengals have won two in a row to get back to 3-3. The Bengals run a complicated defensive scheme that will be a big challenge for Darnold to decipher. It's not a great opponent for a team that has lost two in a row and will be on its backup quarterback.

All that said, I'll go with the 49ers -3.5. Teams rally around backup quarterbacks, and the 49ers have plenty of talent to support Darnold. They've lost two in a row and a team that good usually doesn't drop three in a row. I still have questions about the Bengals, who did beat the Seahawks in their last game but were outplayed.

Either way, there will be a lot to talk about with the 49ers come Monday.

Here are the rest of the picks against the spread for Week 8 of the NFL season, with odds from BetMGM:

Bills (-9.5) over Buccaneers

If the Bills don't have a semi-impressive performance Thursday night, it really will mean we can forget about them for a while. More on this weird matchup in The Daily Sweat.

Rams (+6.5) over Cowboys

Don't let NFL players fool you into believing they take things one game at a time. They know the schedule. And the Cowboys know that next on their schedule is a game at the Eagles. That might be on their minds, even just enough to let the Rams keep it close.

Vikings (+1) over Packers

Maybe this is the popular underdog that everyone takes and loses. Though, the Vikings could be favored by kickoff. Who are you taking, the team that just lost to the Broncos or the one that beat the 49ers? The Vikings are alive and well in the NFC playoff race, and I think they keep the momentum going. The Packers just aren't good (yes, I was wrong about that one).

Falcons (-3) over Titans

The Titans are never an easy out, and the Falcons aren't all that great. But I'm assuming Ryan Tannehill doesn't play through a high ankle sprain (and even if he does play, it's Tannehill playing through a high ankle sprain and I'm not sure that leads to much success), and do you want to back Will Levis against a decent Falcons team?

Colts (+1) over Saints

I keep thinking the Saints will be good, but it's probably not happening. There's just something holding them back. It's not like the individual pieces aren't talented. The Colts are hard to figure out, too. But they are coming off a pretty good offensive performance, albeit in a loss, to the Browns. That said, we're at the whims of which Gardner Minshew II shows up.

Dolphins (-9.5) over Patriots

I don't really believe the Patriots figured it all out before a win over the Bills. It's just that the Bills haven't been very good lately. The Dolphins might not be able to beat elite opponents yet, but they do generally handle bad teams with ease.

Jets (-3) over Giants

It's always going to be a little scary taking the Jets' offense. But the Giants' offense against the Jets' defense? Yeah, that's a lot scarier.

Steelers (+3) over Jaguars

I don't know what it is about Mike Tomlin, but no team wins more "how did they win that?" games than the Steelers. They're the exact opposite of the Chargers that way. So I don't exactly know how the Steelers will win this one, but they usually find a way.

Eagles (-6.5) over Commanders

The Commanders are a bad football team. Every game they have played this season is either a loss or a game they should have lost but somehow won. Ron Rivera is getting closer to being fired, and Sam Howell is flirting with being benched. It's hard to know what will happen first. The Eagles haven't been dominant this season and struggled with Washington the first time around, but I doubt they sleepwalk against the Commanders twice.

Panthers (+3) over Texans

Houston is the better team. But when has that mattered during this NFL season? Carolina is off a bye and has to be hungry for a win. The Panthers face a team that isn't going to overwhelm them, talent-wise. So let's take the home underdog.

Browns (+3.5) over Seahawks

Another P.J. Walker game. It should help the Browns that they knew on Wednesday that Deshaun Watson wouldn't play, instead of stringing it out all week. And they've done a pretty good job rallying around Walker when he plays. Getting more than a field goal seems right, especially if Cleveland's defense rebounds.

Broncos (+7) over Chiefs

This feels like the Broncos' Super Bowl. They've heard a ton about their losing streak to the Chiefs, which dates back to 2015. They played two weeks ago and the Broncos were in the game most of the time. It just seems like a game the Broncos will put everything into, while it's just another game on Kansas City's schedule.

Cardinals (+9.5) over Ravens

The Cardinals were a good bet early on, then not so much. It's hard to keep backing them after watching them lose four straight by double digits. But oddsmakers know nobody wants to take them after they've looked uncompetitive. The spread is high.

Bears (+8.5) over Chargers

The Bears aren't good. Tyson Bagent looked solid last week, but he's still an undrafted rookie out of Division II Shepherd. There are reasons the Bears are underdogs. But who are the Chargers to be laying 8.5 points against anyone?

Lions (-8.5) over Raiders

The NFL gave us three awful prime-time matchups this week. All three games have a spreads of 8.5 points. Detroit looked terrible last week but it happens. The Raiders are way, way worse than the Ravens, last week's Lions opponent, and this looks like a get-right game for Detroit.

Last week: 4-9
Season to date: 51-53-2