How improved plate coverage could reduce k rate

Recently there has been a lot of discussion about baseball having a strikeout problem. Not everyone agrees with that but strikeout rate in MLB is at an all-time high.

Increased K rate didn’t really lead to reduced scoring though since increasing power did offset the reduction in contact. For example in the last 3 years the runs scored average 4.6 runs per game which is  less than the super high scoring around the year 2000 but higher than most years of the 70s to mid 90s before the steroid era kicked in.

This can be attributed to some ball changes but also player development maximizing output per ball in play with optimizing swing path, often called the launch angle or fly ball revolution and also players got stronger, bigger and lifted more weights increasing raw power as well are modern tools like overload and underload training which is an adoption of the weighted balls driveline has introduced 

Those things did help to keep scoring up however it now also starts to reach limits, you only can raise your launch angle so much and get so much stronger. For example league ISO peaked in 2019 and while the recent reduction is probably related to the attempted deadening of the ball it still seems a limit of power output has been reached or at least close to that.

That means to keep scoring up players will either to increase walks or halt the rising of strikeouts. While there are now tools like VR technology to increase plate discipline like this one and this can help pitchers are offsetting that with concepts like tunneling which will make pitch recognition harder. Since walk rate has essentially been constant the last 30 years at 8 to 9% it seems that is an area where you can gain a little but not a huge amount.

While walks didn’t really change in the last 30 years K% certainly did and went up from 15% in the early 90s to 24% this year.

So when power is close to maxed out and walks hardly ever change the thing to attack obviously is strikeout rate and we actually did see that in the last 2-3 years. For example the 2017 WS champion Astros and 2018 champions Boston had the lowest K rate in the league, the 2019 Nats were 5th lowest and the 2020 Dodgers were 3rd lowest. Now this is no guarantee and we still see some bad teams near the top of those low K leaderboards like the 2019 pirates but generally lowering Ks while keeping power at a good level seems to be a good recipe. We did see that with individual players too where good hit tool guys with mediocre power increased some launch angle and got a little stronger and put up good power numbers despite modest maximum Exit velocities (Bregman, Altuve, Murphy even Betts).

The question now is how can we reduce a players strikeout rate. One theory is that swinging for higher launch angles increases strikeouts but I only found a mild negative effect of launch angle on contact

It seems that contact rate to some degree is an innate skill that is not super easy to change. There is some stuff you can do like shortening up the swing or also practicing against high velo machines but there are limits to that. You also can try to reduce chase rate with tools like the mentioned VR tools since outside the zone contact is around 20-25 percentage points lower than inside the zone contact.

However a really interesting stat that has been recently discussed a lot is called strikes%+swinging strikes% (CSW%). This stat basically adds swinging strikes and called strikes and has a pretty good correlation with pitching success, for example last year the leader was Jacob deGrom with 34%. That makes sense because both a called strike and a swinging strike leads you to fall behind in the count and in tune to more strikeouts.

However this still needed to be verified with hitters since with hitters different factors than just contact play a role, especially power.

I looked at the top and bottom quartile of hitters in ISO, wRC+, K% and OBP.

The strongest effect seen was unsurprisingly in K%. The top Quartile of hitters from 2018-2021 to date had a 24.3% CSW% vs 29.1% for the bottom one. Overall the Pearson correlation between CSW% and K% was a strong 0.79. In OBP and wRC+ the effect was weaker but still in favor of the lower CSW% players while in ISO actually the higher CSW% guys had more power. This might be a selection effect as only powerful players with a high CSW% can survice but also maybe related to players being more selective inside the zone and thus improving their batted ball quality as middle pitches tend to be hit harder than pitches toward the edges of the zone.

This leads to an interesting conclusion for player development. In my opinion players with a high CSW% (only 2 of the top30 in wRC+ where above the critical 30% and only 7 above the league average of around 28%) should work on their plate coverage so they can drive more pitches within the zone well and also work on their pitch speed coverage, especially the ability to hit badly located “get me over” breaking balls early in the count when you are usually looking fastball as a hitter. This will reduce the batted ball quality a little but if you have the swing to cover different zones and speeds well this effect can be kept in  check.

Simultaneously that player should also work on pitch recognition to not increase his chase rate too much as he is more aggressive within the zone. A good example of this is Nick Castellanos. He does have a high swinging strike rate (16% last two years while league average is around 11%) but he has a low called strike percentage (around 11% the last years with league average being 16%). This gives him a respectable 23% career strikeout rate despite his big swing and miss issue and his swing is good enough in covering the zone that his batted ball quality didn’t suffer too much (.332 BABIP and .203 ISO for his career). Typically players who have a swinging strike rate of 16% will strike out more like 30% or even more.

On the other hand players with a low swinging strike rate can afford to be a little more selective within the zone and only hit balls in their  hot zones to increase their batted ball quality. Mike Trout is the prime example of this. His swinging strike rate is very low at 6.7% and he is famously good at low pitches and just OK (formerly very bad) on high pitches so he can afford to take a lot of high pitches and target low pitches for a high 20% called strike rate. This means his K rate is slightly higher than it could be if he covered more of the zone but really since his swinging strike rate is so low he doesn’t have to and rather has about an average strikeout rate with off the charts batted ball quality because he only swings at the pitches he can really crush (slightly below the zone up to middle).

He can only afford that though because his swinging strike rate is so low, if he whiffed at a league average rate his approach likely would lead to a 30+% strikeout rate.

Elite contact players with limited power like Madrigal actually should be more selective within the zone since their contact quality is not great to begin with and by focusing on the heart of the zone they can improve that a little zone heart wOBA is better than edge wOBA and they can afford to give up a few more strikes as their contact skill is so great.

CSW% is always composed of swinging and called strikes, so the less swinging strikes you have the more selective you can be within the zone and the more you whiff the more you  should cover the zone to keep strikeouts in check. A CSW% of more than 30% is always a big red flag for a hitter or a hitting prospect and the low hanging fruit (well kinda low hanging since you need to keep chase rate in check) is to cover more of the zone and give the pitcher less “free” strikes if you have a whiff problem.

Obviously this isn’t that easy, as I already said it needs to be accompanied by working on pitch recognition to keep chase rate in check and also working on a clean bat path to all corners of the zone so you can drive the ball straight and not roll over and yank it into the shift.

So to summarize here is what I suggest for hitters with swing and miss issues to reduce their CSW% and strike out less:

1. Working on plate coverage to be able to hit a wide array of pitches to give pitchers less free strikes while keeping batted ball quality up
2. Working on pitch recognition to keep chase rate in check
3. Practice against a wide array of speeds and spins to be able to handle modern pitchers stuff.

There is still value of patience within the zone and not getting yourself out on a pitchers pitch, especially if you have great contact ability and the pitcher is not good but the old sit on your pitch type and location until two strikes might not do so well against modern top pitchers who can throw any pitch in any count. You need to at least be able to cover one thing (big zone one pitch type or small zone two pitch types) because just sitting FB in a certain location means you are not guessing right often enough, especially since you will foul off some of them too.  Exception from that might be 0-0 or 3-0 when you don’t plan to swing much anyway.