So, last week we hopefully learned a few things. Let’s continue looking at leaguewide trends.
In terms of getting on base, not getting on base, hitting for power, and not hitting for power, there are actually four mostlydistinct periods in baseball history for each combination. Define these terms against the historical average and you get:

190118 – Players aren’t getting on base or hitting for power

191952 – Players are getting on base but not hitting for power

195392 – Players aren’t getting on base but are hitting for power

1993presPlayers are getting on base and hitting for power
There are some exceptions, but this paradigm mostly holds true. Here’s another depiction of the “eras” involved:
YEAR (AVG)

OBP (.333)

ISO (.130)

190118

.316

.081

191952

.343

.120

195392

.329

.131

1993present

.338

.158

The periods from 190152 and since 1993 really are quite distinct, but the 195392 period is the hardest to truly peg and kind of has to be squeezed in there. In fact, those figures are quite close to the historical average. Well, actually, the OBP before 1993 is just as much below the average as the OBP after 1993 is above it. When the same era, categorized by offense, includes both 1968 and 1987, there is going to be some finagling.
So, really, there hasn’t been a clear period in MLB history with aboveaverage power and belowaverage onbase percentages, while the “RuthWilliams Era” (191952) had belowaverage power (again, vs. the historical average) but aboveaverage onbase percentages.
Still, breaking things down into four eras is too simplistic. What follows is a walkthrough, not of every season in MLB history, but key seasons, using some of the “metrics” from the first two parts of this series.
1918: .207 XB/TOB, .038 sISOOBP, 95 OBP+, 57 ISO+
In 1918, MLB hitters earned .207 extra bases on average. By 1921, they were earning .300 extra bases after yeartoyear gains of 19%, 8%, and 12%. How much of this was on account of the Sultan of Swat? In 1918, Babe Ruth was already earning .523 extra bases, but had only 382 plate appearances. In 1921, however, he had 693 plate appearances and averaged .717 extra bases. Without him, the 1918 and 1921 ratios change to .205 and .295, respectively. So he’s only responsible for .003 of the increase. (My guess from a couple weeks ago was way off. He’s still just one player.) Perhaps the effect on the power boom of his individual efforts is overstated. However, his success was clear by 1921, so his influence on how other hitters hit seems properly stated. While Ruth’s 11 HR in 1918 tied Tillie Walker for the MLB lead, five other players had 20+ home runs in 1921.
OBP was low in 1918, and most seasons up to that point, but the dead ball era really was mostly a power vacuum. OBP already had two seasons (191112) around the current average, even though it would not get back there until 1920.
1921: .300 XB/TOB, .027 sISOOBP, 104 OBP+, 90 ISO+
So we touched on the 191821 period moments ago. Power skyrocketed, but still to about 10% below its current norm. Meanwhile, OBP was well on its way to a long aboveaverage stretch: OBP+ was 100 or higher every single year from 1920 through 1941.
1930: .364 XB/TOB, .007 sISOOBP, 107 OBP+, 112 ISO+
1930 was the most powerheavy MLB season until 1956 and is even today the secondhighest OBP season in MLB history at .35557, just behind the .35561 mark set in 1936. Nonpitchers hit .303/.356/.449 in 1930. Ten players hit 35 or more home runs, including 40+ for Wilson, Ruth, Gehrig and Klein.
Like we’ll see in 1987, however, 1930 was really the peak of a larger trend: XB/TOB grew 6+% for the third straight year before dropping 14% in 1931 and another 12% in 1933 (with a 9% spike in 1932).
1943: .261 XB/TOB, .028 sISOOBP, 98 OBP+, 74 ISO+
World War II in general was a bad time for hitters, at least from a power standpoint, with 1943 the worst season among them, but 1945 almost as bad. From 194045, the XB/TOB ratio fell 23%. It remained low until 1947. (But even at its lowest point in this time frame in 1942, it was still a better year for power than 1918.) OBP, however, was actually at about its current historical average during the war (within one standard deviation of the mean throughout), so there wasn’t a total offensive collapse. However, it was the first time since the deadball era that OBP+ was below 100. Either way, perhaps the coming look at individual players will tell us what happened.
1953: .365 XB/TOB, .001 sISOOBP, 103 OBP+, 108 OPS+
Thanks to an 11% increase in XB/TOB, it was finally “easier,” relatively, to hit a double or homer than it was to make it to base in the first place. Also playing a role, however, was the OBP; in 1950 it was only harder to hit for power because players were reaching base at a pretty good clip; the OBP+ and ISO+ that year (1950) were 106 and 110.
1968: .320 XB/TOB, .003 sISOOBP, 93 OBP+, 84 ISO+
1968 is often considered perhaps the alltime nadir for Major League hitters outside of the dead ball era, and nonpitchers only earned an average of .320 extra bases per time on base that year. It wasn’t just power that suffered, however, although it did, but it was also the worst leaguewide OBP in 51 years. In fact, OBP was so low, it was actually ever so slightly easier to hit for power in 1968 than it was to reach base.
The thing about 1968 is that, while 1969 featured a lower mound, no 1.12 ERA’s, and a solid recovery for both OBP and ISO, it didn’t automatically revert baseball hitters to their premid60s form. Power fluctuated wildly in the roughly 25year period between 196893.
1977: .378 XB/TOB, .010 sISOOBP, 100 OBP+, 108 ISO+
1977, rather than 1930 or 1987, may be really the flukiest offensive season in MLB history. ISO+ shot up from 83 to 108, after having not been above 96 since 1970. MLB hitters earned 26% more extra bases per times on base than in 1976, easily the biggest oneyear increase in MLB history. XB/TOB then promptly decreased 10% in 1978; it’s the only time that figure has gone up 10% in one year and declined 10% the next. It was the only season where sISO was .010 above OBP from 196784. 35 players homered 25 times or more, the most in MLB history until 1987. 1977 was a banner year for getting on base as well, although, as usual, not as much as ISO. It was the highest OBP season from 197078 and one of four seasons from 196392 with an average OBP vs. the historical average.
1987: .416 XB/TOB, .023 sISOOBP, 101 OBP+, 120 ISO+
1987 has a big reputation as a fluky power season, and players earned .416 extra bases per time on base that year, but that was “only” a 9% spike from the prior season. Additionally, XB/TOB had actually increased every year from 198287, except for a 2% drop in 1984. The 1987 season was mostly the peak of a larger trend, which came crashing down in 1988, when the ratio dropped more than 15% to .353 extra bases. The .400 mark would not be broken again until 1994’s .412, but after that point, this ratio would never fall below the 0.400 it was in 1995.
This season was, however, the only one in the Eighties with an OBP+ over 100. From 196392, in fact, OBP was at or above the historical norm in just four seasons (1970, 1977, 1979, 1987). As with power, however, OBP collapsed in 1988 more so than it had gained in 1987, falling to 1981 levels (97 OBP+).
1994: .412 XB/TOB, .017 sISOOBP, 103 OBP+, 122 ISO+
XB/TOB leapt over 10% from 199293, and another 9.5% in 1994, ushering in a power era that hasn’t quite yet flamed out. 1994 was the year power really took off relative to OBP: in 1992, sISO and OBP were even; in 1993, the gap was still about half of what it would be in favor of sISO in 1994. 1994 also featured the highest ISO to that point, higher than even in the culmination of the mid80’s power trend in 1987. While there would be some years between 1993 and 2009 with modest decreases in power, even in 2013, ISO+ was 112–its lowest mark since 1993. More on the current power and OBP environment momentarily.
19012013: Changes in XB/TOB
Extra bases per time on base was our first choice of metric. How has this particular one changed in certain years?
Overall, nine times has this ratio spiked at least 10% in one season: 190203 (+12%), 191819 (+19%), 192021 (+12%), 194546 (+11%), 194950 (+10%), 195253 (+11%), 197677 (+26%), 198182 (+12%), and 199293 (+10%).
Meanwhile, it decreased by 10 or more percent on six occasions: 190102 (11%), 193031 (14%), 193233 (12%), 194142 (11%), 197778 (10%), 198788 (15%).
2014???
We’ll try to make this a little more interesting: where is baseball going from here? Can we look at these trends throughout history and determine what the next few years might look like?
XB/TOB dropped 4.8% in 2013. It was the sharpest oneyear drop since a 5.6% fall in 1992, but that season only preceded a power boom. Both were modest declines historically, and this one is unlikely to portend much. However, this year’s 112 ISO+ was a new low for the poststrike era.
Yet the bigger issue in 2013 was a stagnant OBP, which has been below the current average since 2009 after being above it every year since 1992. OBP never deviates very much from its norm, but 26/30 seasons from 196392 featured a below average OBP.
Will OBP continue to stay low? It has fallen every year since 2006, from .342 to .323, which represents the longest continuous decline in MLB history. It may be unlikely that it decreases further, but the belowaveragesince2009 fact is worrisome if you enjoy offense. Stagnation for such a length of time has nearly always been part of a larger trend, mostly in the dead ball era and that 30 year period from 196392.
One thing we can probably say is that the “Steroid Era” is over. From 19932009, OBP+ was never below 101 and ISO+ never below 109. Take 1993 out of the sample, and ISO+ is never below 118, and from 19962009, 14 years, ISO was 20% or more above the historical norm every time.
But since 2009, that 20% threshold has never been reached, although 2012’s ISO+ of 119 comes close. Nonetheless, power from 2010present has yet to reach mid90s, early 2000s levels. Power could still increase in the future, but likely for reasons other than PED’s (although the Melky Cabreras and Ryan Brauns of the world always leave a doubt).
If I had to guess, power and home runs are here to stay, even if 2000’s .171 stands as the highest nonpitcher ISO for years to come. (That really is a crazy figure if you think about it: nonpitchers that year hit for power at roughly the career rates of Cal Ripken or Ken Caminiti. In 2013, they were down to more “reasonable” levels similar to Johnny Damon or Barry Larkin.)
The onbase drought is more of a concern for offenses, however, but because OBP is so consistent, that OBP drought could be persistent, but minor.
This concludes the leaguewide observations of power and patience. Part IV next week will look at things like “X players with an OBP of Y and ISO of Z in year 19something.” Part V will then look at individual players. Maybe we can even wrap up with the ones who started this whole series: Joe Mauer, Rickey Henderson, and Wade Boggs. I guess we’ll have to find out.
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