It makes the most sense for the Giants to play this out for as long as possible. The entire offseason was geared towards this exact lineup. They have managed to tread water, pitching-wise, since losing Bumgarner, and they should just keep doing what they’re doing until he gets back. And even then, they should give it a couple of months after he gets back.
In short, the Giants should do absolutely nothing about their situation until the season is over and they have a chance to evaluate their club at full strength. At some point, you just have to allow baseball to happen and ignore the consequences. Since it’s “still early”, you could make the argument that these games don’t matter, which means, really, no games have to matter if your goal is to constantly evaluate the team you spent putting together over a hard offseason.
Johnny Cueto was amazing last night and if he pitches this way all season long, the Giants will be able to compete in a lot more games.