Guzman is starting because the team is desperate. Sure, most guys should be able to go 100. But Guzman is a special circumstance. Likewise, Marshall, with no history of big inning in a season is somebody to look out for overworking (in general, every young pitcher should be protected from overwork, no 23 year old should be throwing 120 pitch games). Because of Guzman's special circumstance you have to take special care of his arm. Ideally he could go 100+ with ease, but these aren't ideal times. The bullpen is not at risk of being overworked right now, and there are reinforcements in AAA if any one guy does get overextended early (not to mention, now we have a starter in the long relief role). Worrying about overworking your relievers, who are by definition your least valuable arms, instead of worrying about your starters, who are much more valuable, is just plain foolish.