Ben Lindbergh of Baseball Prospectus takes a look at five relievers being converted to starters this spring and ranks how well he thinks both will succeed. He puts Neftali Feliz right in the middle. Here's part of what he says about Feliz (you can read the rest here if you have an insider account).
Feliz's secondary stuff has stagnated during his extended stay in the bullpen, and in the rotation, his blistering fastball can't quite carry him like it did in relief. He also saw some significant decline in his peripherals last season, striking out batters at only a league-average rate for relievers (7.8 per nine) and walking too many batters to boot (4.33 walks per nine).
Lindbergh notes that Feliz will have to improve in those areas, something Feliz is focused on this spring.
He's got more notes about his calculations and how he formulates his list. Click here to read all of that (insider).