The Paths to the Playoffs

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We all know the Mariners are not likely to make the playoffs this year. FanGraphs has their playoff odds at 27.9% and Baseball Prospectus gives them a 25.9 percent chance of being in the playoffs. There’s a 75% chance the M’s won’t make it, and we all get to debate whether they should buy, sell or stand pat. To help me think about the question I wanted to look a little deeper at the times when Seattle does make the playoffs. I was wondering

  • What does the rest of the season look like when Seattle makes the playoffs?
  • When are the M’s likely to make a consequential move up the standings?
  • More specifically, is anything that happens in the last 8 games of July likely to make enough of a difference to change those odds?

To look a little more deeply at that I did my own Monte Carlo simulation of the rest of the season and drilled down a bit into those simulations where we do make the playoffs. This was a simplistic attempt that guessed the winner of every remaining game based on the log5 formula which takes the winning percentages of two teams and figures out the odds of a particular team winning. For example two teams with the same expected winning percentage will win a game between them exactly 50% of the time over the long run. If a .600 team faces a .500 team it will win 60% of the time, but if it faces a .400 team it will win 69% of the time since it is significantly better.

The first question is what "expected winning percentage" I should use for each team. At first I tried season-to-date pythagorean projections, but my results were not quite right. It hit average-ish teams on-the-money compared to other projection systems, but teams with high run differentials (Cubs +151) or low ones (Reds -152) were projected to have historically great or poor seasons even though the grown-up projection systems were more tempered. Luckily BP’s aforementioned playoff system actually publishes the input winning percentages for their simulator, so I just stole those:


My simplistic simulation took those inputs and produced very similar outputs for win totals over 10,000 runs.

Team Average Wins
TEX 88.2
HOU 86.3
SEA 83.2
LAA 73.5
OAK 72.0

I only computed the playoff odds for Seattle, but they came in at 12.0% chance of Seattle winning the West and 11.9% chance of a Wild Card for a total of 23.9%. It’s a couple of percentage points lower than BPs 25.9%, but close enough for FanPost work. So let’s drill into what a Seattle playoff seasons looks like. First the data from above, with more detail. Here are the results of all 10,000 runs for comparison with the playoff seasons.

wins 86.33 73.53 71.96 83.23 88.22
std 4.06 4.09 4.02 4.06 4.05
25% 84 71 69 80 85
50% 86 73 72 83 88
75% 89 76 75 86 91

So the 50th percentile is 83 wins and the 75th percentile is 86 wins. Not promising. Here’s what it looks like the 12 percent of the time when Seattle wins the West. Almost by definition, the vast majority of these are above that 75th percentile performance for Seattle.

count 1198 1198 1198 1198 1198
wins 83.76 73.03 71.99 88.76 85.22
std 3.05 4.06 3.88 2.68 2.85
25% 82 70 69 87 83
50% 84 73 72 89 85
75% 86 76 74 91 87

So, to win the West, we expect Seattle to have above a 75th percentile output and both TEX and HOU to have around their 25th percentile. At first blush it seems like ALL of those things will happen together less than 12% of the time, but remember that these aren’t independent events. If Seattle wins the West it will be because it beats TEX and HOU more than expected, pushing down their win totals. I’ll come back to this, cause it’s relevant to when we could hope the M’s make a move to the top.

What about the wildcard seasons? Here’s what the West looks like in those cases.

count 1189 1189 1189 1189 1189
wins 86.66 72.84 71.46 87.47 88.64
std 4.40 4.05 4.04 1.84 4.33
25% 83 70 69 86 85
50% 87 73 71 87 89
75% 90 76 74 89 92

In wildcard scenarios, Seattle wins 87 games on average, while Texas wins the division.

Alright, so does what the Mariners do until the end of July matter much? Will it change your buy/sell scenario? I looked at scenarios where Seattle goes at least 6-2 for the remainder of July vs the Blue Jays, Pirates and Cubs (yeah right) vs 2-6 for the rest of July. Did it make a difference?

Finish Number of Simulations Playoff Percent
6-2 or better 278 (2.7%) 27.8%
2-6 or worse 415 (4.2%) 22.9%

Not much. This probably significantly understates how much the playoff percentages will actually move. If Seattle goes 6-2 vs those teams, it will be perceived as a higher quality team and will be expected to win more games than I’m estimating going forward. I didn’t run my simulations "hot", that is, I didn’t adjust the underlying team quality based on results as we go along.

But wait, what if the M’s triple-sweep the Cubs, Pirates and Blue Jays? It could happen right? My simulation says Yes! It did happen 10 times (0.1%). Of those 10 simulations, Seattle made the playoffs in 4 of them. Alright, but what about if we have a good week AND Houston AND Texas have bad weeks? Well, that’s just so unlikely to happen that there’s not enough data to tell. So basically nothing that happens this week should affect buy/sell sentiment very much. We know enough - what happens this week isn’t that relevant.

If we won’t learn much in July, when will we have a good sense that the M’s are headed to the playoffs? Not for a while. Here’s how the standings progressed in the playoff simulations (West and Wildcard combined).

Aug 1 55.85 47.47 46.38 51.82 60.25
Sep 1 71.19 60.23 58.74 67.74 74.11
Oct 4 85.20 72.93 71.72 88.12 86.92

What?? The M’s are way behind both Houston and Texas going into September in the scenarios when they are expected to make the playoffs? How can that be? Well, the key is to look at the schedule. Between August 29th and the end of the season the M’s play the Rangers 7 times and the Astros 6. The rest of their games are against lousy teams: 7 vs Oakland, 6 vs the Angels, and 3 vs the Twins. The only exception is three against the Blue Jays who are also in the wildcard hunt.

Here’s the crazy thing. My projections expect the M’s playoff-bound teams to average 67.739 wins at the end of August. The non-playoff scenarios? 67.747. Almost exactly the same. The way the schedule is set up, the M’s make the playoffs by staying around .500 until September and then beat up on the division, going 20-10 like it’s May or something. It’s not exactly likely, but it sure would be exciting. I say stand pat and hope for a thrilling run to October.