Do Star Players Age Differently?

I want to start this piece by acknowledging that the idea for it didn’t come from myself or Kevin or one of the other staff writers. It came from Pat in the comments section of the last piece I did on aging. Here it is:

I would also be interested in seeing how superstars relate to this model. In other words, normal mortals tend to have a certain career trajectory. Do those who are transcendent age differently? Not outliers like Barry Bonds, but players who are really great ?do they peak later? longer?

Before I get into the meat and potatoes of this piece, I want to invite any reader who has interest in us expanding on an entry to feel free to request it. Chances are the research has already been done and we’ll be able to churn to make it happen without much effort. For the initial piece on aging in question, I probably logged four to five hours for research and another one to two to analyze it. I’ll have this piece researched and written in under two because the data set was already there.

Of course, I would invite anyone to suggest any topic. We won’t be able to do all of them, but we’ll do our best and consider anything proposed.

Do Star Players Age Differently?

Looking around the Majors, teams invested over two hundred million dollars on players age thirty-four and over. Some players have a track record of being elite players. Others still have work to do to cement that legacy. I’ve already looked at how players age in general, but now it makes sense to take it a step forward to see if stars age any differently.

In order to write about how a star player ages, I think we first need to identify what a star player is. For me, it’s someone who performs at a high level over the course of an extended career. Having one or two outstanding years doesn’t qualify you to be a star. That gets you flash-in-the-pan status and it probably also makes you an outlier in the normal aging process. For me, a star hitter is one who can average 3.5 WAR over twelve seasons or achieve a career WAR of 42. I also created a subcategory for position players of good regulars who attained a career WAR of 24. For starting pitchers, I see stardom at 3 WAR over twelve seasons or 36 WAR. I was a little easier on relievers expecting 1.5 over ten years but only four from the sample qualified. As a result, I didn’t even include them in this piece.

After breaking the hitters down into their three groups, I noticed that star players tended to arrive earlier than the rest of the sample. In fact ten of the nineteen bats who qualified reached the majors by the age twenty-one. To give that some context only eight of the other one hundred nineteen players in the sample made it that young. That’s over fifty percent compared to under ten percent and doesn’t include Ichiro Suzuki on the star side, who debuted in Nippon League at eighteen. While progress wasn’t as linear with the samples chopped up, star hitters tended to peak earlier experiencing their best year collectively at twenty-six, though they rebounded and experienced similar years at twenty-eight and twenty-nine. Good and marginal players exhibited a clear peak at twenty-nine.

That’s not to say it was all downhill after the stars hit thirty. The group collectively averaged more than 4 WAR in their thirty and thirty-one seasons and between 2.4 and 3.7 WAR a season from thirty to thirty-six. Interestingly, the 3.7 WAR year came at thirty-five, but I’ll have more on that later. The good hitter group ranges from 1.8 – 2.9 WAR between thirty and thirty-four before dramatically falling off. While they’re not the players they once were, stars tend to stay incredibly useful even in the late stages of their career while good players stay good, but not for long.

To put it another way, if you chart every 3.5 or better WAR season for the players among this sample, 57% happen before the age thirty season, but 43% still happen after.

Pitchers are a different animal as star pitchers tend to have a surprising double dip. The good and marginal sample top out around age twenty-seven and the stars also hit the first and smaller of their two peaks a year later. Their true peak comes at age thirty-one. When I noticed this, I presumed it was an issue of outliers throwing off the small sample. In truth, seven of the ten pitchers met or exceeded their production level from four years earlier. None had fewer than 3 WAR and seven exceeded 4.5. In the end, the late peaked seemed legit.

Stars averaged 3.9 WAR in their thirty-two season before dipping below 3 the following year. They have an age thirty-four spike before finally hitting the fatal decline starting their thirty-five season.

That late career spike for both pitchers and hitters intrigued me. I have no way to quantify it but I have my suspicions that it’s caused by the “best shape of my career” factor. We all know the story. Star player has an off year after thirty and media and fans start talking about how these guys should save some dignity and retire already. That player in turn realizes that they need work harder than they used to in order to get the most out of their body. They in turn get off the plane in Florida or Arizona in the “best shape of my career.” That extra boost of fitness only gets a player so far and, whether they like it or not, they end up tailing off anyway.

In the end, stars do age differently than their peers. Hitters peak a little earlier while pitchers peak a bit later. Regardless of where they peak, though, they outperform the lesser cohorts at every age level and you can even expect better production from a star player in their mid-thirties compared to a good player in their early thirties. Star players get big money late in their career for one very simple reason. Even though they’re not their best, they’re still very good and probably better than the alternative. That doesn’t even consider how important that players name lends to the franchise’s overall value. They’re still worth it on the field.