MLB total bases props: how to research the number

Total bases add up the bases earned on hits: a single is one, a double two, a triple three and a home run four. Walks, hit-by-pitch, stolen bases and reaching on an error add nothing. The usual number is 1.5, with 0.5 and 2.5 on some boards. Over 1.5 needs two bases, which one extra-base hit can supply alone. Settlement uses official statistics, and the treatment of a hitter who does not play varies by operator.

Settlement rules to check

• Power versus contact

  Four bases from one swing makes extra-base power the engine of this market. Two hitters with the same batting average can have very different distributions if one collects singles and the other turns a share of his hits into doubles and home runs.

• Lumpy outcomes

  Most games end at zero, one or two bases, with an occasional home run game that lands at four or more. Because of that skew, the average sits above the typical result, and a line of 1.5 can be harder or easier than the mean implies.

• Pitcher type and handedness

  A ground-ball pitcher turns hard contact into infield outs, while one who works up in the zone allows more balls in the air. Handedness and pitch mix also decide whether a particular hitter can drive the ball to the gaps.

• Park and weather

  Fence distances, altitude, temperature and wind direction change how far batted balls carry. Warm air with a wind blowing out raises the odds of extra-base hits, while cold, heavy air with a wind blowing in suppresses them.

• Plate appearances and bullpen

  Each extra trip to the plate is another chance at a double or home run, so lineup slot and the team's expected run environment matter. A shaky bullpen can also mean late power chances against relievers who throw in the middle of the zone.

• Role changes and sample size

  Power numbers are noisy over a few weeks. Look at quality of contact over a longer window, and note changes such as a new spot in the order, a position switch or a return from injury that may alter how freely he swings.

1. 1Check the lineup slot and whether the hitter is platooned, since both change the number of plate appearances available.
2. 2Separate his singles from his extra-base hits over a long window so that one home run streak does not dominate the picture.
3. 3Look at the starter's ground-ball, fly-ball and home-run tendencies against this handedness.
4. 4Note the park, temperature and wind forecast, and confirm whether a roof will be open or closed.
5. 5Build a range of outcomes across zero, one, two, three and four-plus bases rather than a single expected total.
6. 6Compare the chance of clearing the line with the break-even probability of the price, and see how much the gap shrinks if weather or lineup changes.

• Counting walks and steals

  Walks, hit-by-pitch and stolen bases add nothing to total bases, so a patient hitter who reaches constantly can finish with zero. Use the hit distribution, not on-base percentage.

• Forgetting the two-base threshold

  A 1.5 line needs two bases, so one single is not enough. A hitter who mostly produces singles depends on getting two hits, a different path from one extra-base hit.

• Using the mean as the likely result

  An expected total of 1.4 does not mean the hitter usually gets one or two. The distribution is uneven, so judge the chance of clearing the line directly instead of comparing averages.

• Counting on one home run in the sample

  A single multi-homer week can lift an average without changing the underlying skill. Check whether the contact quality that produced the home runs has actually been consistent.