Baserunning Risk Calculator

Carlos Martinez was dominant last night, working nine scoreless innings. However, Jeff Samardzija was also spectacular and the game headed to the bottom of the ninth scoreless. Matt Carpenter laced a double off the left field wall to lead off the inning when he made the bold decision to round second and head for third. With no outs, the ball hit out to left (where a throw to third would travel a much shorter distance), the fact that Carpenter wasn't sprinting out of the box compounded with the fact that he initially began to slow down pulling into second, and the 4-5-6 hitters due up, it made little-to-no sense for Carpenter to chance taking the extra base. That is where I got the idea to create this calculator.

Here's how it works. There is a metric called RE24 which assigns an expected run value to each of the 24 possible base-out combinations. For example, with runners on the corners and one away, the average number of runs that score that inning is 1.14. For reference here are all 24 expected run values.

Runners 0 Outs 1 Out 2 Outs
Empty 0.461 0.243 0.095
1 _ _ 0.831 0.489 0.214
_ 2 _ 1.068 0.644 0.305
1 2 _ 1.373 0.908 0.343
_ _ 3 1.426 0.865 0.413
1 _ 3 1.798 1.140 0.471
_ 2 3 1.920 1.352 0.570
1 2 3 2.282 1.520 0.736

The calculator needs five pieces of information to tell you whether taking the extra base was worth the risk

  1. The run expectancy if the runner stays put
  2. The run expectancy if the runner advances safely
  3. Will the runner score if he takes the extra base?
  4. The run expectancy if the runner is out advancing
  5. The odds of the runner advancing safely
Here's how to use the calculator in practice. In the third inning of this Friday's game against the Giants, Dexter Fowler hit a triple to open the frame. Tommy Pham flied out to centerfielder Denard Span for the first out. At that moment Fowler had two options: stay at third or break for the plate.

Also on the spreadsheet are the RE24 values that you can copy and paste as needed. In the case, the answer to those five questions were:
  1. Runner at third with one out; .865
  2. Bases empty with one out; .243
  3. Yes, Fowler would score; 1
  4. Bases empty with two outs; .095
  5. Pick whatever odds you so choose; for the sake of this example let's say 90%.
Copy and paste that info into the spreadsheet and if the runner should have tried to advance, the F2 cell will read TRUE. If the runner should have stayed, the F2 cell will read FALSE.


The calculator works off this expression that I devised:

x=RE if runner stays

y=RE if runner is safe

z=RE if runner is out

a=Runs scored

b=Odds of advancing safely


If this looks like another language, don't worry about it. All you have to do is fill in the boxes and the computer will do the rest.

To access and use the calculator click here. From there click on "File" where you can make a copy of the spreadsheet if you have a Google account or you can download it as an Excel spreadsheet. (I am a Mac user and the Excel file still works in Apple's Numbers program.) I need to give everyone their own copy, otherwise multiple people would be trying to fill out the same spreadsheet simultaneously.Screen_Shot_2017-05-21_at_11.00.13_AM.0.pngHere's to anguishing over future Cardinals baserunning blunders. I hope you enjoy!

As always you can follow me on Twitter @Tyler_Opinion

Go Cards!


If you check the link now there will be a tab (see comments for picture) at the bottom marked "One Run" which you can click on to see this new spreadsheet. Everything works exactly the same except this calculator addresses the probability of the batting team scoring one run, not estimating the total number of runs scored that inning. This calculator should be used primarily for late game situations (like the Carpenter play last night) when pushing one run across is the goal. For potential walk-offs put a zero in the "ORE if runner advances safely" cell (the game is over) and a one in the "Runs scored if runner advances safely" cell.