What are the implications of moving Ivan Nova to the Yankees' bullpen?

Yesterday, the Yankees announced that they were moving Ivan Nova from the rotation to the bullpen. Nova didn't join the team until the middle of the season after being activated from the disabled list following his Tommy John rehab. Throughout his career in the Yankees' rotation, Nova has had some good seasons and some bad seasons, and this is shaping up to be one of the bad ones. Since being activated in June, Nova has thrown 75.2 innings with 5.47 K/9, 3.09 BB/9, 1.19 HR/9, 5.11 ERA and 4.92 FIP. In his most recent start, he gave up six earned runs in less than two innings against the Blue Jays. It makes sense to strengthen the rotation by removing Nova from it, but the move also has some downsides as the postseason approaches.

First and foremost, moving Nova to the bullpen could mean that Masahiro Tanaka won't be lined up to start the potential Wild Card game. The Yankees' last game of the regular season is Sunday, October 4th. The AL Wild Card game will be played Tuesday, October 6th. Since Nova has been pulled out of the rotation, Tanaka will start Friday's series against the Mets. If the Yankees stay on rotation, then Tanaka's schedule for the rest of the season would look like this:

9/23 Tanaka vs. Blue Jays
9/28 Tanaka vs. Red Sox
10/3 Tanaka vs. Orioles

If the division title comes down to the wire and the Yankees still have a fighting chance going into that last weekend series again the Orioles, then there's no way that Tanaka will be starting the Wild Card game. That could open the door to the possibility of Luis Severino making the start instead. Of course, the Yankees can reevaluate the rotation after they get through the six games against the Mets and Blue Jays. If the division is out of reach at that point, then they can rearrange the rotation so that Tanaka is lined up for the Wild Card.

Removing Nova from the rotation also means that the Yankees won't be able to use the six-man rotation that they've discussed since all the way back during spring training. Today is the last off day of the season, which means that the Yankees have to play 17 straight games before the season ends in October. Before Nathan Eovaldi went on the disabled list, the Yankees had planned to use a six-man rotation when CC Sabathia came off the DL, but they haven't been able to find a way for it to work. Since they added Adam Warren, they could have used a six-man rotation with Nova, but it appears that they didn't trust him to start one of the critical games against the Mets or Blue Jays. The Yankees don't have any good options for a starter who could make a spot start down the stretch, either. Bryan Mitchell hasn't pitched more than one and a third innings since he went on the 7-day disabled list in August, so he doesn't appear to be stretched out, not to mention the fact that he hasn't pitched well. Chris Capuano has given up 10 runs during his last two appearances. It remains to be seen how effective Nova could be working out of the bullpen, but since they removed him from the rotation it seems that the Yankees wouldn't use him to make a spot start. It looks like the Yankees will have to stay on rotation for the rest of the season without getting any extra rest, unless Eovaldi somehow gets healthy ahead of schedule.

Did the Yankees make the right decision by taking Nova out of the rotation? Should they throw in a spot starter somewhere to get everyone extra rest heading into the post season?