I don't know how much longer to give Gray. He had one really nice start, but his other three have been horrible. At least Anderson has been decent against everyone except St. Louis. Do I take a shot at Pomeranz or hold onto Gray for another start?
Don't drop Chase Anderson.
I would also hold on to Jon Gray for now. He will get that ERA back on track. If both Gray and Pomeranz stay healthy (which neither has a great track record of doing) then I think they will get the same number of strikeouts but Pomeranz will likely get more wins. If you look at their career Pomeranz has pitched more than 150 inning twice in his much longer career than Gray, who has only done it once.
If those are the guys you are looking to drop then I don't think Pomeranz will help your lineup too much anyways.
I would drop Gray over Anderson. Is it worth it for Pomeranz.... maybe. Take the risk because Pomeranz has more upside.
I would say neither should be dropped for Pomeranz. Anderson has been solid and Gray can be very useful if you pick and choose his matchups (ie start him away and only start at home against weak opponents).
Pomeranz is sold in Ks and should be in Ws given he plays on the Red Sox, but his ERA and WHIP are likely to be a mess. Among his likely most common opponents, the Yankees, Blue Jays and Orioles are all top 10ish offenses against LHPs. He's also likely to be injured again before long.