Kyle Seager and the No Good Very Slow Start

Alex B. Rivard
4 min readFeb 10, 2021

My wife and I were at a conference in Austin once and, coincidentally, the Mariners were in Houston. This was the brief, amazing period when the Mariners were first in the AL West right before the rest of season decline.

I packed my Seager jersey, my wife her Paxton jersey, and we drove from Austin to Houston for the game. We got in early for BP and Seager came over to greet some visiting fans. Obviously I ran up to say hi but he was only signing stuff for the kids — class. An Astros fan asked Seager “Are you pitching tonight?” a befuddled Seager replied “…n…no”. The man then turned to me and asked “Who was that?”. I showed him the back of my jersey. “Oh, Sayger. You only know him because you’re from Seattle”. Incredible.

This is the first part in some brief retrospectives about Kyle ‘Sayger’ Seager, my favourite M. I’m going to briefly look at his month-by-month trends over his career given that there seems to be a general consensus (at least on r/Mariners) that Seager suffers from slow-starter syndrome. That his Aprils are generally not great but he picks it up by mid-season.

I’ll only present a couple figures in this piece. Below, I plot Seager’s mean monthly wOBA over every season he’s played using Fangraphs data. I’ve removed the handful of games in March when the season started early and I’ve removed the handful of regular season games when the season ends in October. Obviously, October has been removed entirely because, well, yeah. Sigh.

The above figure plots Seager’s average wOBA by month. I’ve excluded his rookie season in 2011 and the most recent season in 2020. Couple things of note. It does seem, for the most part, that Seager is a slow starter. Note the upward trend from April to May in 2012, 2014, 2015, 2016, and from May to June in 2019 (remember he showed up BSOHL in 2019 and got injured in Spring Training). So while this confirms initial suspicions, it’s also worth noting that he started well in 2013, 2017, and 2018 before falling off at the end of the season.

It’s actually those end of season datapoints that are the most concerning to me. To see what I’m getting at, the figure below plots his month-by-month career averages.

The below figure plots Seager’s mean wOBA in each month over his total career. The horizontal line represents his career average wOBA (2011 and 2020 excluded). His mean April wOBA is only slightly below his career average but note the decline in August and September. End of season declines can be seen in the above figure as well, in 2013, 2014, and 2016 (even if this was his best season by fWAR to date).

Ultimately, I think Seager’s slow starts are a bit exaggerated. The below table lists his career month-by-month mean wOBA (basically the above figure in table form) as well as the standard deviations for each month. Note Seager’s largest standard deviation is in his first month of April and his lowest standard deviation is the last month. We can expect more variation surrounding Seager’s starts (as is demonstrated above, in fact) and more consistency around those expected September performance such that we expect Seager’s wOBA performance to be between 0.284 and 0.364 95% of the time but his September performance ranges from 0.286 to 0.346 95% of the time.

I think Seager’s starts are perfectly average but highly variable. His ends are a bit more worrying in that there appears to be an end of season decline.

A little caveat to this. I wanted to compare Seager to league average across all seasons but that’s more work than I’m committed to. I also wanted to compare him to third-base averages but, again, too much work. The Fangraphs data is amazing but as far as I can tell, you can’t parse it by position (unless I’m misreading the instructions?). I’d like to get a better global analysis of this but that might take some time.