I first reported on this issue in a post last year Did The Increased Use Of Relief Pitching Cause A Decline In Clutch Hitting? Back in the 1950s and 1960s, as I show at this earlier post, hitting in non-close and late situations was not much better than in close and late situations. But, as I also showed, as the use of relief pitching grew, batting averages and isolated power started to decline, relatively, in close and late situations. So it looks like it might have been easier to hit well in the clutch in the "old" days.
Recently Tom Tango (aka tangotiger) had a post titled Best and Worst Clutch Hitters of the Retrosheet era .
Tom has a clutch stat based on WPA or "win probability added." The idea there is that every plate appearance by a hitter either increases or decreases his team's probability of winning. A HR with the score tied in the bottom of the 9th has more impact than one in the first inning with the score 10-0.
But Tom adjusts this by how often a hitter gets to hit in "high leverage" situations. Then that it is compared to what his WPA would be if he always hit in average leverage situations. I hope I got that right. But, of course, Tom explains it much better. That stat ends up telling us how many more games a player's team wins (or loses) because he hits better or worse in high leverage situations than he does overall. It is just called "Clutch."
To see if this stat changed over time, I took all the players with 4000+ PAs from 1950-2009 and found their Clutch/PA (758 players). Then I found the the year which was the mid-point of each player's career (the data all comes from Baseball Reference which showed the first and last year of each guy's career). Of course, that is not a perfect way to do it since that may not be finding the exact middle of a player's career in terms of PAs. But it is a reasonable approximation. Call this mid-point "Year."
Anyway, the correlation between Year and Clutch/PA is -.12. That is, as time goes on, batters are doing worse in the clutch. That makes sense given the increasing use and specialization of relief pitching. The -.12 is small, though. But, as time went on, there were more players reaching the 4000 PA minimum because there were more teams and in the early 1960s, the season grew to 162 games. So any correlation will have alot more guys from the later years when everyone was doing worse in the clutch. This waters down any correlation we might find (by the way, if you are interested, Yogi Berra, famous for being a clutch hitter, ranks 37th out of 758 players).
But if we look at the top and bottom 25 in Clutch/PA, we can see some interesting trends. The table below shows the top 25 along with their mid-point year.
If you look carefully at the mid-point years, you can see that there are more players from earlier years. But this will be summarized below. The next table shows the bottom 25.
It actually turns out that the top 25 has a disproportionate number of guys from earlier years and the bottom 25 has disproportionate number of guys from later years. The next two tables shows this. The first table shows what percentge or share of the 758 players comes from each decade.
The next table shows how many players were in the top 25 and the bottom 25 from each decade and the expected number based on the percentage from the table above. 2.18 is about 8.7% of 25, for example. Notice that the 1950s had 4 guys in the top 25 while its expected number is 2.18. The 1960s and 1970s also had more guys in the top 25 than expected. We can also see that the 2000s had none in the top 25 even though 4.49 were expected.
The 1950s, 60s and 70s did not have as many guys as expected in the bottom 25 while the 1990s and 2000s had more than expected. So it could be that it is harder to hit well in the clutch now than 4-5 decades ago. My guess is that this is due to relief pitching.
Update July 26:
I divided all the players into 6 groups since there are about 6 decades. And since 758/6 = 126.33, I looked at the top 126 and the bottom 126. The table below summarizes how many guys from each decade were in each group along with the expected number.
The 1950s don't have as many as expected in the top 126 and more than expected in the bottom. But the 1960s do have more in the top and fewer in the bottom. Same for the 1970s and 1980s. But the last two decades are very much under-represented in the top and very over-represented in the bottom. So this suggests it is harder to be a good clutch hitter in current times.