2017 in review: A brief post-mortem on the Mariners season

With the League Championships wrapping up soon and the World Series right around the corner, the baseball season has hit its climax. For every other team in baseball, it’s a time for reflection before the calendar turns to the offseason. Zach got us started yesterday and we’ll have much more for you in the coming weeks.

For my part, I’d like to present a graph chronicling the Mariners offense and pitching throughout the season. The data points are taken from each of my series previews from May onwards. It may not be the most robust dataset but it’s gives us a twice-a-week glimpse at how the team performed against league average. I’ve plotted team wRC+, and team FIP- from both starting and relief pitching on the same plot.

There are no real surprises here. It’s hard to imagine the starting rotation ever being above league average, but that’s where it stood after a month of play. But it all felt apart quickly and the rotation remained around 18% worse than league average for the rest of the year. An improvement in September provides some promise since it coincides with the arrival of Mike Leake. But it wasn’t just Leake, the entire starting rotation posted the sixth lowest FIP- in the majors during the last month of the season.

The trend line for the relief corps is almost the opposite of the rotation. A really poor start to the season would eventually be reversed by the end of July. The Mariners benefitted from strong performances by Nick Vincent and Emilio Pagan in the second half of the season. With a rotating door at the back end of the bullpen, I’m actually pretty surprised they ended the year with a FIP- above league average.

With most of the narrative focus on the pitching staff and the injuries it suffered, the offense few under the radar for most of the season. And while they maintained a wRC+ above league average for almost the entire year, their ability to score runs faltered somewhat during July and August. The team scored just 4.2 runs per game during those two months. It didn’t hurt them in July—their best month by runs allowed per game was in July too—but it really caught up to them in August when they allowed 5.4 runs per game. The offense bounced back a bit in September but it was too little too late.

What sort of trends do you see? Does this graph align with the narrative you’ve built for the 2017 season?