Dellin Betances is in a good place this spring, both mentally and physically. But that does not mean the eighth inning will belong to him. It’s a new mix-and-match world for the Yankees’ bullpen. Aroldis Chapman is the closer, but the rest is up to the game situation. “Chapman is the closer, but other than that it’s matchup-based,’’ Aaron Boone told The Post on Monday night before the Rays beat the Yankees, 4-2 at George M. Steinbrenner Field. “I think Dellin has had a really good spring,’’ Boone said. “I think his delivery is in a great place, I think he is in great shape. I think his command has been good. I think his stuff has improved each outing so I think he is getting close to regular-season game ready. I think he is in a good spot.’’ That spot does not necessarily have to be in the eighth inning. The Yankees have a monster bullpen and will use the arms where they see fit. So it could be David Robertson, Chad Green, Tommy Kahnle or Betances in the eighth. Betances, who has the most relief innings in the majors over the past four years, pitched 38 times in the eighth last season and 24 times in the ninth. By the end of the season Betances’ confidence was shaken and the Yankees eventually had to go to other options. This has been a spring when Betances has rebuilt his body, mind and approach. Betances pitched a perfect seventh and eighth Monday night, getting four Ks.