Charlie Hustle: Doing Lines

Sportsbook at the MGM Grand in Las Vegas

One of the most common questions I get when it comes to betting baseball games (and sports betting in general) is how in the world to read all the various lines.

Like a Miami Dolphins OL Coach we’ll be doing all the lines today.

Most sports fans are at least casually familiar with the concept of a point spread like you’d see in a football game. So we’ll start there.

Even opening up the ESPN app puts the point spread for Monday’s College Football National Championship right in your face.

“Sports betting is not mainstream” – an idiot

Alabama is favored in the game by a margin of 4 points.

Favorites are denoted by negative (-) numbers while underdogs have positive values (+). To win a point spread bet placed on Alabama, they must win by at least 4 points. Inversely, a winning bet on Georgia requires only that Georgia be within 4 points of Alabama on the final scorecard.

Georgia can lose the game, but a bet placed on them could still win… which is how degenerates are born.

A couple final score examples:

ALA 24 / UGA 21 (21+4 = 25) : ALA W & UGA Bet W

ALA 35 / UGA 30 (30+4 = 34) : ALA W & UGA Bet L

ALA 24 / UGA 28 (28+4 = 32) : UGA W & UGA Bet W

ALA 42 / UGA 14 (14+4 = 18) : ALA W & UGA Bet L *

*This qualifies in my metrics as a “trouncing”, stay tuned for a future Otter Room post on the analytics behind a trounce. Sidenote: this score also gives me 2012 PTSD.

To determine the winner on a point spread bet, simply add the (+) point spread value to the underdogs final score. The winner of that adjusted game is the bet winner.

The point spread is what keeps gamblers interested in a game like Alabama vs. Little Sisters of the Poor. Yes, Alabama is going to win… but can they win by more than 40?

The concept of a point spread does exist in baseball betting in the form of the run line.

However, baseball run lines alone tend to be pretty uninteresting and almost always sit at -1.5 for the favorite on rare occasions moving up to -2.5 in a particularly lopsided matchup. Baseball is lower scoring and since a run in baseball is worth “1 point” where a touchdown is worth “6 points” the scoring differential itself tends is less volatile.

Where things get interesting is when you start comparing run lines with moneylines.

The moneyline determines how much a given bet pays out. For a point spread bet in football the line almost always sits at -110. A complete “line” for a point spread in the CFP National Championship might read something like this:

ALA -4.0 (-110) / UGA +4.0 (-110)

A negative moneyline states how much you’d need to wager on a bet in order to have it pay out $100. So when betting either side of this point spread, you’d need to wager $110 to win back $100.

A positive moneyline (let’s use +110 for this example) states how much a wager of $100 would pay out. So a $100 wager pays back $110.

American moneylines follow the formula above, but over in jolly old England they use a Decimal representation of the moneyline. A Brit placing a bet on the ALA/UGA point spread would see something like this instead:

ALA -4.0 (1.9) / UGA +4.0 (1.9)

The decimal value represents the bet return as a multiplier of your wager. A $100 bet on the point spread will return your $100 plus an additional $90.

I actually find the American system unnecessarily confusing, and generally convert moneylines to their decimal representation when dealing with lines in code. In Python, that looks something like this:

def convert_line_to_multiplier(line):
    if line>0.:
        return line/100. + 1.
    return 100./abs(line) + 1.

Easy peasy.

Betting the point spread gives you a little extra leeway to win your bet on a dog, but at the price of a less rewarding payout.

If you wanted to bet the Natty Ship straight up, purely taking the winner of the game with no point spread cushion. The odds look like this:

ALA (-190 / 1.53) / UGA (+160 / 2.6)

As expected, Alabama straight up pays out less than against the spread with a 4 point disadvantage. While Georgia straight up pays out more since you’re banking on them taking down the Tide.

In baseball this straight up moneyline is the primary means of placing bets on games. In fact the run line wasn’t officially introduced in major sportsbooks until the 2013 MLB season.

However, the run line can offer some interesting opportunities. Because there’s so little ability to fluctuate run lines based on score differential (recall that the majority of baseball run lines sit at -1.5/+1.5) , books will entice bettors to take run lines based on the associated moneyline.

For example, a team could be +1.5 on the run line and that bet could pay out +200… what?

Yup, you can place $100 on a team to be within one run of a win (and still lose) and that bet will return your $100 plus $200 more.

This doesn’t happen particularly often and it turns out the bookies out in Vegas are pretty smart, so the majority of these bets fail.

However, one of the most interesting things about sports betting is that you can have a losing record, but still be up money. The key is not so much picking winners as it is picking the right winners whose payouts overcome your losses.

In the next post I’ll explore some advantages to be found in baseball data and how we’ll use them to build a model for picking the right teams in 2018.

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