Jul 14, 2013; Flushing, NY, USA; New York Mets former playerhits during the 2013 All Star Legends and Celebrity softball game at Citi Field. Mandatory Credit: Brad Penner-USA TODAY Sports

Former Mets catcher Mike Piazza is a big, muscly guy who hit a lot of home runs. A couple of sources have noted that he, over the course of his career, had issues with back acne (a symptom typical of, but not exclusive to steroid users).

He also played in the 1990’s / early aughts. So he did steroids, right?

Come on, he had to.

Everyone was doing it.

How else did he get that kind of power?

…Maybe he was just good at hitting baseballs?

Among MLB hitters in the liveball era (since 1920), Mike Piazza is probably one of the best power hitters. He ranks 45th (.237) in isolated power (ISO) and 47th (427) in home runs. He was also a good hitter in general – his .308 batting average ranks 55th. What makes most of this astounding is that he accomplished the majority of his offensive resume as a catcher – the ISO and home run marks are both MLB records for the position.

But some argue these numbers are tainted. They say Piazza took performance enhancing drugs illegally and/or immorally, and that such drugs padded his numbers. Did they?

Well, for that to be true, there needs to be some evidence that his numbers were “enhanced”. Ostensibly, home run power wouldn’t be the only benefit of performance enhancing drugs, but no one’s ever argued about Piazza’s ability to hit for average (nor his very good plate discipline) being tainted. It’s the dingers, because PEDs = dingers & strikeouts.

The simplest way to measure power is looking at ISO. It’s calculated by subtracting slugging percentage from batting average, and thus measures total bases beyond first per at bat. Singles are worth 0, doubles 1, triples 2, home runs 3. Add that all up, divide by at bats, and you’ve got a number representing how much power a guy hits for. For reference, the MLB (non-pitcher) average hovers around .160.



So let’s look at Piazza’s ISO by season* compared to his career overall. I’m including his minor league numbers, but they’ve been separated into individual levels instead of seasons. I also omitted his 1992 major league stats as he only accumulated 79 plate appearances. Put it all together, and you get something vaguely resembling this:

*Seasons listed by player’s age on January 1st of calendar year

For the most part, you have a fairly smooth, clear career arc: steady improvement heading into a solid prime, and steady decline. Oh wait, that’s not so steady. How do you explain his age-33 season, where his ISO dipped from .264 to .197? How do you justify such a precipitous decline in 2003 – the year after androstenedione was banned by the MLB?

Sep 29, 2013; New York, NY, USA; New York Mets former catcher Mike Piazza speaks during his induction into the Mets Hall of Fame prior to the game against the Milwaukee Brewers at Citi Field. Mandatory Credit: Brad Penner-USA TODAY Sports

Piazza only played in only 68 games that season (his fewest since a September 1992 call-up). He was out from mid-May to mid-August with a “grim” groin injury. It was expected that he would miss the season; at that time his slashline resembled .333/.462/.613 – a healthy .280 ISO entirely in line with his career to that point. In his first 15 games back – up to the end of August, he hit .261/.426/.522 – an ISO of .261 that still met expectations. He struggled badly in September, failing to hit a home run and posting an OPS of only .547.

2004 saw a similar pattern, though Piazza avoided the disabled list. He hit an entirely Piazza-esque .297/.388/.506 with 16 home runs. Again, he struggled mightily in the second half – .200/.305/.310 with only 4 dingers.

At age 36 in 2005, Mike experienced a small bounce back. There’s a decent reason for it too: the Mets started taking it easy on him. As the year went on, Piazza’s production increased as his workload decreased – he posted a .169 ISO in 75 first half games (297 PA), and a .272 ISO in 38 second half games (145 PA). The Padres followed that pattern and got a successful 2006 out of Piazza. Keeping him fresh allowed him to experience his best power season in a few years – his highest ISO and home run total since 2002.

Occam’s razor suggests that the simplest hypothesis is often the correct one. Piazza’s decline was somewhat accelerated by injury. But his ability to hit for power was largely maintained, especially when the load of catching regularly was reduced. Could him quitting ‘roids be an explanation for his decline? Perhaps if we actually had an idea how to quantify the effect of performance enhancing drugs, yeah. But it’s most likely the result of an aging catcher who averaged 137 games behind the plate over 10 seasons with a significant, career-altering groin injury.

But that’s not enough. Comparing him to other big power hitters of the generation, we can somewhat contextualize Piazza’s power in the steroid era. Below is a chart listing ISO by age (like the one above) that includes multiple big power hitters of the 1990’s: Barry Bonds, Mark McGwire, Sammy Sosa, Jason Giambi, Craig Biggio. For reference, David Wright is also included.

*See above chart for season explanation

What jumps out is that Mike Piazza’s “power” stayed dramatically more consistent than the other big power hitters of his day. The wild spikes and dramatic variations that peppered the careers of Mark McGwire and Jason Giambi are absent from Piazza’s resume, as are the superhuman peaks of Barry Bonds and Sammy Sosa. 31 seasons shown represent an ISO above .300 – none by Mike. More than any other player on the graph (save for, perhaps, fellow victim of the era Craig Biggio), Mike Piazza’s career arc most represents what you’d expect visually from a player’s career; his numbers improved somewhat steadily into his early 30’s, and would have declined smoothly were it not for a significant injury and the wear and tear of playing catcher every day into the second half of his 30’s.

Mike Piazza was a big, muscle-y guy who hit home runs in the 1990’s. He also showed very good disclipline and even stole five bases once. He admitted to taking androstenedione before it was banned in 2003. There’s a corresponding decline, but it’s neither as dramatic nor as inexplicable as some of his counterparts. Unless you assume that either

(A) Mike Piazza was consistently taking performance enhancing drugs and continued to after 2002

or

(B) Performance Enhancing Drugs don’t tangibly enhance a player’s performance

there’s not a lot to suggest that Piazza’s career was tainted by illegal PEDs. If you believe he stopped in 2002, it’s hard to explain the sustained stretches of Piazza-in-his-prime dominance he displayed in 2003-06. If you believe that the PEDs kept him healthy, you’re fighting what’s perhaps a more difficult argument in trying to morally qualify elective medicine. What would make it materially different than the amphetamines players – like Hank Aaron – took in previous decades for the specific purpose of easing the rigors of a 162-game season?

I’m not going to get into the actual steroid debate here**, because I don’t think I have to. The argument championed by blogger-by-a-different-name Murray Chass is that the drugs boosted his power and were responsible for making him into the greatest hitting catcher of all time. It fits the narrative. He’s a big, muscle-y home run hitter – a 62nd round pick no less – who put up Hall of Fame numbers. He was a nobody!

But it’s an uphill battle to suggest that with disappearing bacne and a single testimonial from a player on a different team are your exhibits A and B. There’s no smoking gun, only smoke.

The numbers just don’t support it. “Eye tests” and “gut feelings” aside, the numbers are what matter here. No one got into the Hall of Fame just looking the part (seriously, google Babe Ruth).

So where’s the real evidence?

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** In full disclosure, I believe that players in the “Steroid Era” should be in the Hall of Fame regardless. Aside from the fact that we make significant moral assumptions about past players, we’re pretending that an entire decade of baseball history didn’t happen. We all cheered ignorantly (perhaps feigned ignorance) when McGwire and Sosa’s home run chase effectively saved baseball. We enjoyed the Bash Brothers in Oakland. We also fail, at times, to recognize the magnitude of a player’s career ending, and the fact that the majority of those we label cheaters are players fighting to stay in the show and not those who are gunning down records.

When Warner Brothers released the Looney Tunes DVD collections in 2003 (fitting given the topic at hand), they included the following disclaimer:

“The cartoons you are about to see are products of their time. They may depict some of the ethnic and racial prejudices that were commonplace in American society. These depictions were wrong then and are wrong today. While the following does not represent the Warner Bros. view of today’s society, these cartoons are being presented as they were originally created because to do otherwise would be the same as claiming these prejudices never existed.”

We shouldn’t be trying to sweep the era under the rug. While we shouldn’t necessarily be in the business of honoring ill-gotten achievements, we have no business ham-fistedly policing the bygone product of our tacit excitement and greed. Tell your children that some players made some morally-questionable decisions, and tell them about the fun we all had watching it happen. They’ll probably learn a better lesson from us recognizing the struggle to capture ever-fleeting greatness – which is perhaps the essence of sport – than from us batting a blind eye to those who make morally-reprehensible ones that we ignore because driving drunk or domestic violence have nothing to do with sockin’ dingers.