Perhaps the BEST B1G Forum anywhere, here at College Football Fan Site, CFB51!!!

So what am I missing?  Why is Mich favored by 18?

Michigan has been dominant in all their games. Rutgers is 3-0 but is also 2nd in the nation in turnover margin and had less than 200 yards of offense against Syracuse. They've been a better version of Rutgers but also a bit lucky. Michigan leads the nation in rushing. If Rutgers can force them to pass, this could be a game. But that is easier said than done.

Michigan has been very dominant, and 18 seems fair to me. But then, I haven't seen Rutgers play.

The line may be impacted  by folks' memories of Rutgers in part, and Michigan.  I don't know how much the line is impacted by folks who don't pay much attention to the game, some perhaps?  A line of 18 struck me as "about right" but I don't know much about either team.

I've said before that a Vegas line isn't necessarily what they think the outcome of the game should be, the line is set where the oddsmakers think there will be a 50/50 split on the betting. Vegas is designed to make their money off the vig. If betting is 90/10 Vegas has risk--the house might win big, but they also might lose big. If betting is 50/50, Vegas has zero risk. Half the bettors will win, half will lose, and Vegas makes money on the vig regardless of which half is which.

So yes, perception may affect Vegas lines. Fanbase size may affect Vegas lines. I.e. there are a lot more Michigan fans in the US than Rutgers fans, and Michigan fans are more likely to bet their team than Rutgers fans, so there is a nonzero built-in betting base for Michigan that doesn't exist for Rutgers. The oddsmakers take these things into account when setting lines. 

If Rutgers can force them to pass, this could be a game. But that is easier said than done.

Michigan has better WR's than people give them credit for. Cornelius Johnson is better and faster than people think he is. Dude can really run, and he's big. He's done some things that have really made me go wow this year. AJ Henning & Roman Wilson can both fly- both just haven't gotten the targets because the passing offense sucks and they don't pass the ball much. Henning has shown his speed and burst on punt returns and reverses. Wilson popped a reverse for about 50+ and flashed his speed. 

They just need to get the opportunities. Haven't gotten them yet.

I've said before that a Vegas line isn't necessarily what they think the outcome of the game should be, the line is set where the oddsmakers think there will be a 50/50 split on the betting. Vegas is designed to make their money off the vig. If betting is 90/10 Vegas has risk--the house might win big, but they also might lose big. If betting is 50/50, Vegas has zero risk. Half the bettors will win, half will lose, and Vegas makes money on the vig regardless of which half is which.

So yes, perception may affect Vegas lines. Fanbase size may affect Vegas lines. I.e. there are a lot more Michigan fans in the US than Rutgers fans, and Michigan fans are more likely to bet their team than Rutgers fans, so there is a nonzero built-in betting base for Michigan that doesn't exist for Rutgers. The oddsmakers take these things into account when setting lines.

For the most part, lines are set using power rankings based on mathematical formulas. Those numbers used preseason data, often recent success and recruiting rankings as part of their predictors (which create better predictors). SP+ isn’t fully in line with Vegas, but it’s often a good barometer.

In SP+, this would’ve been 25 points in the preseason. Michigan is out gaining teams by 3.4 yards per play and outscoring them by 3.75 points per drive. Rutgers cut into the number by a TD, but it’s hard to catch up to a team playing like that. (Preseason stuff filters out and is replaced by in-season stuff, but it takes more than three games)

The Line is an interesting thing.  Obviously the House will win nearly every time with the Vig if they balance the bets, no reason to mess with a sure thing.

I have wondered if major programs with a lot of fans get a larger line as a result, but then, bettors would know this and offset it to the point it disappeared.

I've said before that a Vegas line isn't necessarily what they think the outcome of the game should be, the line is set where the oddsmakers think there will be a 50/50 split on the betting. Vegas is designed to make their money off the vig. If betting is 90/10 Vegas has risk--the house might win big, but they also might lose big. If betting is 50/50, Vegas has zero risk. Half the bettors will win, half will lose, and Vegas makes money on the vig regardless of which half is which.

So yes, perception may affect Vegas lines. Fanbase size may affect Vegas lines. I.e. there are a lot more Michigan fans in the US than Rutgers fans, and Michigan fans are more likely to bet their team than Rutgers fans, so there is a nonzero built-in betting base for Michigan that doesn't exist for Rutgers. The oddsmakers take these things into account when setting lines.

I have not bet on sports. So, explain for me this . . . does the betting line change over time with the bets placed on each side of the game, as it does in pari-mutuel betting at my local dog track (which will no longer exist after 2022)?