When Baserunning Matters

The Diamondbacks are great at baserunning. Their runs from baserunning was outstanding for the last six seasons. Details are in the following table:

data from Baseball Reference

Coach Dave McKay’s attention to details was a key part of that achievement. He was interviewed by Jack Sommers of the AZ Snakepit. After saying he looked at videos of that day’s pitchers, he said, “There’s more there - but I might be getting into the finer stuff that other guys aren’t looking into. So I want to be a little careful talking about just what I do look at!” Without revealing any secrets, let’s explore baserunning.

How can baserunning make a difference when homers are not happening and hits are sparse?

One answer is one-step-at-a-time increases in run expectancy, which makes it easier to score runs. Four ways to do this are stealing bases, bunts, taking extra bases on hits, and pinch hitting.

Stealing bases. A foundational skill is that each runner must know the pitcher’s time to the plate compared to his time to second base. Then, he must be alert to any added advantage that tells him to steal the base.

The baserunner can gain an advantage if he perceives and recognizes ‘tells’ of the pitcher. ‘Tells’ could include what the pitcher always does as he commits to throw to the plate, does the pitcher’s grip allow the runner to distinguish between fastball vs offspeed, or determine how likely that the pitch will be in the dirt. That information will help him decide whether to steal on that pitch.

The game situation matters. Matt Popwitz wrote an article that explained that with a weak batter at the plate and two outs, there is more to gain and less to lose by attempting to steal second base.

Knowing that base stealing plays can be reviewed, a base stealer must keep contact with the base when his slide is completed. Generally the defender keeps the tag on the runner just in case. The instant replay made stealing more difficult.

Knowing that infield shifts create opportunities for stealing bases, baserunners are alert to take advantage of those opportunities. Three opportunities are a) a fielder is positioned too far from his base to get there before a runner who decides to steal that base, b) a fielder allows a huge lead to a baserunner, and c) general confusion about fielder responsibilities.

Technology has given teams new tools to help them decide when to steal a base. Amazon Sage Maker developed a model that determines success probability of stealing second base. Although it looked at 37 variables, the most significant may have been runner’s speed and burst, the catcher’s average pop time to second base, game situation, and pitcher characteristics (handedness, time to the plate, and frequency of each type of pitch).

What do the statistics show about stealing bases? In 2020, Tim Locastro stole 4 bases without getting caught. Although 18 teams had more stolen bases than the Diamondbacks, efficiency is very important. For second base, the Diamondbacks’ 79% success rate ranked 9th in the Majors. That 79% success rate tells me that stolen base attempts were worthwhile because a FanGraphs study indicated that the breakeven was between 70% and 75%. However, the Diamondbacks success rate stealing second fell from the previous season’s 87.5%. Will the Diamondbacks reach that higher level next season?

Bunts. Diamondbacks waited until September to attempt sacrifice bunts. Speedster Tim Locastro had two sacrifice bunt attempts and the team’s only success. For all teams in the 2020 season, successful bunting-per-attempt was higher in the following situations (data from Stathead):

• Zero outs vs one out (61% vs 26% success).
• Lone runner on second (68% success).
• Runners on first and second (66% success).
• The only bunt attempt of the game (69% success).

Russell Eassom looked at 2010-2105 seasons and had a similar observation: Bunting with no outs and either lone runner on second, or runners on first and second, increased the probability of scoring one run 4.6% and 6.6% respectively. Perhaps next season the Diamondbacks will attempt more sacrifice bunts in those game situations.

What about bunts in extra innings? In 2020, 31 sacrifice bunts happened in 224 extra half-innings. Alex Bires calculated that half-innings with sacrifice bunts had a higher chance of scoring at least one run (77.4% vs 55.5%), and a higher run expectancy (1.39 vs .84).

Taking extra bases on hits. Baserunners can take extra bases when the batter hits a single or double. In 2020, speedster Tim Locastro was 41% successful taking an extra base, which was below the 48% average for the Diamondbacks (ranked 5th in the Majors). Extra base possibilities follow:

• Runner on first base, batter hits single, runner attempts to reach third base. The Diamondbacks 38% success rate ranked 6th in the Majors.
• Runner on first base, batter hits double, runner attempts to score. The Diamondbacks 38% success rate ranked 20th in the Majors.
• Runner on second base, batter hits single, runner attempts to score. The Diamondbacks 66% success rate ranked 9th in the Majors.

Impact from pinch hitting. Pinch hitting can create better match-ups of batter-pitcher. A favorable matchup could change the impact of a stolen base.

Position flexibility of players like Daulton Varsho will give Torey Lovullo more chances to create favorable matchups via pinch hitting. Favorable matchups when combined with aggressive baserunning will win more games.

Perhaps because of difficulties in creating advantageous matchups, in 2020 the Diamondbacks had 26 pinch hits (only 4 teams had fewer), with a negative Wins Above Average (WAA) (ranked 14th in the Majors). The top-3 teams in pinch hitting WAA (Rays, Dodgers, and Mets) averaged 39 pinch hits, suggesting that the Diamondbacks could gain wins with increased frequency of pinch hitting.

Summary. The Diamondbacks are excellent at baserunning. Next season when baserunning matters, it’s likely they will improve in four areas: stealing bases, bunts, taking extra bases on hits, and pinch hitting.