Strikeouts per nine innings (K/9) and left-on-base percentage (LOB%) are often closely correlated. According to FanGraphs.com, “Most pitchers have LOB%s around league average (which is approximately 70-72%, depending upon the season), and pitchers that deviate from that average tend to see their numbers regress towards average in the future.” The MLB average LOB% from 2008-present is 72.4%.
However, if a pitcher has a high strikeout rate, it’s reasonable to expect he’ll also have a high LOB%. Also according toFanGraphs.com, this is because “Pitchers that record a high numbers [sic] of strikeouts can pitch their way out of jams more easily than pitchers that rely upon their team’s defense, so they are able to maintain LOB%s higher than league average.”
Take a look at the correlation for yourself over the last seven-plus seasons:
As K/9 rises, LOB% rises. As K/9 falls, LOB% falls.
From 2008-11, Giants pitcher Tim Lincecum struck out 9.96 batters per nine innings and stranded 77.2% of baserunners. The National League averages during that time were 7.19 K/9 and 72.4 LOB%. So Lincecum had both averages beat handily, and that was perfectly explainable.
Moving to the present, Lincecum’s K/9 has decreased each of the last four seasons, from 9.19 in 2012 to 7.00 in 2015 (even after striking out eight Marlins in six innings in his last start). As Lincecum’s K/9 has decreased, so has his LOB%—that is, until this season.
Indeed, Lincecum’s LOB% fell from 78.5% in ‘11 to 67.8% in ‘12, and he couldn’t manage to reach even 70% in ’13 or ’14.
This year, however, Lincecum’s LOB% is 81.7%, despite having the lowest K/9 (7.00) of his career. Here’s a closer look:
The most likely explanation is luck. Even in last night’s start there were three or four times Lincecum was bailed out by outstanding outfield defense. Additionally, the Marlins hit a few balls that looked like home runs off the bat that died and found gloves (or the wall) in the cold and expansive AT&T Park.
Another factor to Lincecum’s success is his HR/FB ratio. From 2012-14, 13.5% of fly balls allowed by Lincecum were home runs. Even from 2008-2011, Lincecum’s dominant years, his HR/FB ratio was 7.25%. This year, it’s a microscopic (and unsustainable) 3.6%.
But one of the more curious and intriguing facts about Lincecum’s 2015 season is his ground ball rate. For Lincecum’s entire career before this season, he induced ground balls at a rate of 46.7%. He’s never had a season in which it was higher than 48.9%.
So far this year, it’s 54.0%. The N.L. average GB% from 2008-present is 45.2%. Tim Hudson, who throws a sinker, has a career GB% of 58.1%.
So Lincecum’s high GB% and low HR/FB rate make sense taken together. And they suggest that we could be looking at something more than just luck.
Lincecum has always had tremendous downward movement on his pitches. If he’s learned to harness his movement and pitch toward the bottom of the strike zone, the high ground ball rate could be sustainable. (This could, of course, cause a sustainable dip in his home run rate.) And the Giants infield boasts some top defensive talent in Brandon Crawford, Joe Panik, and Bradon Belt. So more ground balls would help Lincecum in a number of ways and could revitalize his career.
But inducing more grounders should be a matter of control if it’s intentional, and Lincecum’s 3.49 BB/9 this season is almost identical to his career average of 3.50. So it might be unrealistic to think that Lincecum suddenly has newfound command of his pitches.
Only one thing is certain. Lincecum is a very different pitcher now than he was when he took the league by storm from 2008-11.
With the new Tim Lincecum, we should absolutely expect his LOB% to regress toward league average (~72%) because of his below average strikeout rate.
A sustained high ground ball rate, then, seems like Lincecum’s only hope of becoming highly effective at this point in his career. With ever decreasing velocity and strikeout rates, Lincecum’s must continue to induce lots of ground balls and limit home runs. We don’t know if this will happen, but the numbers indicate that it just might.