At What Age is a Hitter’s Projection No Longer Reliable?

I blame my podcat mate Rob Silver for today’s study. First, he stated this:

The history of 35-year old first basemen having seasons like what everyone think Votto is gonna do is almost non-existent.

Now Hall of Fame players do Hall of Fame things but everyone just assumes the curve goes back up – and I hope it does but man….

— Rob Silver (@RobSilver) February 6, 2019

And then he said this:

Nelson Cruz hit 41 homeruns last year.

He’s awesome.

Super safe player to draft.

He’s 39 this year.

In the history of baseball one player has hit more than 40 homers at 39 or older – Barry Bonds.

Three players hit > 36 (Bonds, Hank Aaron, Papi)

Only 7 hit > 30.

— Rob Silver (@RobSilver) November 18, 2019

Of course, players age. Some quickly. Some not as fast. While few hitters remain productive into and past their mid-30’s, I needed a simple rule on how to deal with these vets. I found one and since I need to provide content to be paid, so does the world.

To perform the analysis, I examined how hitters met their projections as they crept up in age. To do this, I took a hitter’s Steamer projection (back to 2010) and found how close it was to that season’s actual results. And I’m also including the previous season’s results. It was not obvious I needed this value. It was pivotal to finding a simple solution and helps verify some of the work from The Process.

Note: For player valuation, I’m using my 15-team 5×5 NFBC valuation from last season.

I grouped the players who projected to produce $15 or more in return by age. Then I found the median and average amount this group missed their projections by. Also, I divided this group by those who were projected to exceeded or not meet their previous season’s production. And here is the data.

The Steamer projections are a little ambitious but are consistent over the different ages by missing on average (blue line) between -$5 and $0. Also, if a hitter is projected to outperform their previous season, they will, on average, miss on their projection by a larger range. This finding agrees with the study in The Process.

One anomaly does stick out. From age 32 and older, the difference between those expected to beat previous production and those that don’t get wider (the difference between yellow and red line). For the age-32 or older batters, the two groups differ by $6.30. For those 31 and younger, the difference is $1.7.

With this analysis, I am just not going to give any top hitter over the age of 31 any more credit than they did the previous season. Now, as the talent pool thins, I’ll gladly take a chance on these distinguished gentlemen, but not until then. I can’t have the core pieces on my team imploding on me.

Using our current Depth Chart projections, here are the $15 or better hitters who are going into their age-32 or older, their 2019 production, and their projected 2020 values.

The one name which immediately comes into play would be Martinez. Projections have him producing $32 of value but he was just worth $28 last season. For someone going in the second round, I’m going to give myself a little cushion to work with him since these veterans normally produce at a $26 range ($32-$6).

I was getting to the point where I was afraid to roster any older hitter so I would just stay away and miss out on some bargains. Instead, I’m just more cautious of them by limiting my expectations to their previous production levels. By following this rule, I’m hoping to limit the downside while not completely ignoring older hitters.