How non-"playoff" was the Mariners rotation — Updated

Back in September as the season was winding down, we used 2016’s playoff teams in taking a peek at exactly how far off the Mariners were in 2017 from being productive enough to propel, or at least not take away from, a playoff push.

With the 2017 regular season now in the books, I’ve updated that research using 2017’s playoff teams to collect that same data.

If you didn’t check out the original piece, each rotation above is sorted by fWAR, with the most valuable pitcher on a team being referred to as the #1, the second most valuable being listed as #2, etc, even if the rotation isn’t necessarily listed that way on the official depth chart. For the purpose of this research, in the event that a team didn’t have five starters with a full season’s worth of starts, more than one pitcher may have been combined to generate the total fWAR for that rotation spot.

After compiling that table for both 2016 and 2017, this is what I found most surprising:

The fWAR accumulated by the starting rotation for a playoff team in 2017 was almost identical to that of 2016. (Just for fun, I calculated that same average in 2017 without the best rotation of all time included, and that number dropped to 14.4). Despite the fact that starting pitchers in 2017 made up the lowest amount of total wins above replacement since the MLB expanded to 30 teams (and fewer fWAR than 12 different seasons prior to that, even), playoff teams still tended to be blessed with strong rotations.

Here’s the average fWAR of each rotation spot for those 10 playoff teams from 2017:

And surprising again, the near nonexistent change in fWAR from playoff rotations was even distributed almost exactly the same:

This additional year of data to add to the sample size reinforces the conclusions made from analyzing 2016’s playoff rotations: while the Mariners do not need a star-studded rotation in order to finally reach the promised land once again. They simply need league average performances from the back end of their rotation in order to give the team a chance to win on any given day.

The Minnesota Twins just made the playoffs while receiving just 8.3 fWAR from their starting rotation. The Mariners finished 2017 with 6.4 fWAR racked up by their top five starting pitchers (note that some of those “pitchers” were several guys combined for ~32 starts). While a team should by no means game plan on sneaking into the playoffs on the back of 8.3 wins from their rotation, the Twins—and an incredibly weak American League Wild Card 2 race—just showed us that it is indeed possible to qualify with a rotation that unimpressive, and the Mariners were roughly one league average starter away from that threshold. It’s a longshot to bet on that happening again, though, and the Mariners need more. Just a bit more.