I haven't kept up with what the options are that are out there. I will say that based on the quality of this team and the rest of the division (they're not that good - not good enough that one guy will make them a playoff favorite - but they should still win the division and sneak in for a puncher's chance in the playoff derby), I don't want to see them cash in a couple of long term chips for a short term rental. At that point their minor league talent surplus would be left pretty low for what I perceive to be little increase in their chances for this season. Last year, based on the overall strength of the team and their one clear flaw, I liked cashing in a shiny chip for Chapman, and it likely made the difference in the playoffs (notwithstanding Maddon's game 6 and 7 mismanagement of Aroldis). This year, such an acquisition - this time for a quality starter rental - might increase their chances of winning from, say, 10 to 12 percent.
I'd rather see them pursue one of two paths:
1) Be aggressive and unload several quality chips for a cost-controlled starter (Sonnie Gray??? meh, unless the scouts think his arm is getting stronger again beyond what the numbers show. Who else might be on the market?) that can help them beyond 2017. Then spend on a quality free agent to help rebuild their rotation in the winter, or...
2) Be conservative and make a relatively low-cost deal for a competent #4/5 who can eat innings and bounce out Lackey and his 5.88 FIP from the playoff rotation (and full rotation once Hendricks returns). This should help nudge them over the top for the division, and improve them a bit for October.
The middle pathway - dealing just some of their quality chips for a quality 2 or 3 type rental (assuming that is an available option) is unappealing. Such a deal would yield a minimal gain in their chances for this season, at the cost of pinching the window and likelihood for this team to be a consistent playoff team in coming years.