In the discussion about how best to set up the Nationals' 2014 playoff rotation, invariably the big question seems to be whether Gio Gonzalez or Tanner Roark deserve the fourth and final spot. Here today I will argue that the decision is really not as simple as all that, given how Doug Fister has pitched this year. No, Fister has not had a bad year, but he is not pitching as dominantly right now as he could be.

To understand how good these pitchers have been, let's look at the whole rotation one more time. First, let's look at their stats for the season to date:

I won't dig into all the details yet, but this chart shows why people might not trust Gio. His ERA is by far the highest on the team, as is his walk rate, and giving away free bases is simply not considered good baseball. Apparently he tries to make up for it by allowing fewer hits than everyone else, but who pays attention to that?

Gio's walk rate is the reason that he trails the pack in walks plus hits per nine (WHIP * 9), and what a pack that is. Though Roark does not stand out in any other category, he just barely edges Zimm, Fister and Strasburg in the number of baserunners he allows overall. That is a tight rotation.

Did you see Fister's shiny/sparkly/gleaming ERA? Did you see how his peripherals for the year scream that that ERA is not sustainable? That ERA is a full run lower than his career stats. It's a nice stat worth celebrating, but an ERA is never something you can take to the bank or to the playoffs.

This is the postseason though, and games in April, May and June do not matter here. Let's look at how these five have performed over their past six starts:

Over his past six starts, Gio has been quite good. He is not walking as many batters as he was earlier in the season, and he's still the toughest to hit off of. It is clear that Gio is going into October strong.

Roark has been solid but not outstanding in his recent starts, but I can only say that because frankly he's being compared to Strasburg, Zimm and Gio here. Roark's numbers are very consistent, and the fact that he has lowered his walk rate recently is a good sign that he is at the top of his game going into October.

Fister of the nice and sparkly ERA missed a part of the season to injury, but he came back strong. Unfortunately, he is apparently fading here in September. His walk rate is up considerably, he is getting hit more and his ERA is getting less sparkly. Over his past six games, Fister has been by far the weakest link in this rotation.

Fister has been better his past few starts, though. Let's look at only the past three starts:

Over the past three starts (a small sample size by any measure), every single member of the rotation has been outperforming their season averages. Roark comes off looking bad because he is being too consistently good rather than sparkly streaky good like Fister. Gio only walked one batter in three games. Fister walked six, raising his BB/9 to new heights. All three are having success right now by one measure or another.

When I started this article, I intended to show that Gio should be a lock for the rotation and that it is Fister that should be in the competition for the 4th spot. Now that I have dug through the statistics, I am less sure how I would proceed if I were making the decision.

#TeamGio - Gio appears to be in top form heading into October. Though his one postseason experience was far from perfect (still better than J-Zimm), in his career he has more innings under his belt than any other member of the Nationals rotation. Having a lefty in the rotation could be a big deal against some playoff opponents. Gio is not the best pitcher on the team, but going into October his walk rate is under control and he is pitching very well. #lefty

Gio has had the worst season overall, but has improved a lot and is finishing strong.
Strengths: lefty, veteran
Weaknesses: historically wild

#TeamRoark - Tanner has been consistent all season long, and he has only improved with time. This year he pitched more innings than he ever has in the past. Maybe his arm is not as fresh as those Fister or Gio bring, but he is still consistently getting excellent results right now, and isn't that what you look for from your 4th starter in October? #consistency

Roark has been consistent start to finish.
Strengths: consistent
Weakness: inexperienced

#TeamFister - Doug has more postseason experience than the rest of the Nats rotation combined. With the Tigers he started seven playoff games and pitched well under pressure. That said, Fister has been by far the weakest member of the rotation in recent weeks, with a walk rate that is worrisome on a guy known for his control. Is experience more important than dominant control in the playoffs? If he could fix his control, he'd be a no-brainer. #experience

Fister has allowed the fewest runs this season, but his trademark control has faded of late.
Strengths: post-season experience, historical control
Weaknesses: recent control issues

All three guys have the stuff needed to pitch in a playoff game. Their career FIP and xFIP are ridiculously similar, suggesting that no one of the three is by default the best. Each brings something valuable to the table, but each comes with a question or two as well. Do you value Roark's consistency or do you gamble on a hot streak from Gio or Fister?

Setting aside the issue of bullpen experience, which of these three would you cut from the rotation and why?

Taking bullpen experience into account, do you choose a different name? Roark has pitched 22.2 innings in the bullpen with good success. Fister has pitched 5 innings in the bullpen with great success. Gio has pitched 15.2 innings in the bullpen with terrible success.

It's a tough decision, but I'm fairly certain that the Nats will end up with a first rate rotation in the playoffs no matter who is left off.