From the article-
"Ben Baldanza built Spirit from a tiny startup into the nation’s leading ultra-low-cost carrier."

"Start up"? Did this guy even do any research?

"Spirit’s gigantic 30% growth for 2015 was likely a mistake. The expansion made each flight less profitable than before. That doesn’t mean the Spirit model won’t work. Spirit will probably fare a lot better if it stops flooding the market with seats and gets customers to prize its service along with its prices. "

With that logic, we should go down to 0 planes, because we will make the most money that way. We make more money every airplane we add, and we lower fixed costs at the same time. At no time will an 80 plane "start up" ever "flood" the market with seats. I do agree about the customer service, though. I hope it gets better with the new guy.