While the Giants are still in postseason contention as of now and actually have a better record than the Cardinals, they're going to have a tough time getting back in the race for the NL West crown with the Dodgers pulling away and the Diamondbacks and Padres also in front of them.
In the event that they don't get back in the race, we could see them sell off a few pieces. Alex Wood might be a good option. The veteran left-hander had been out for some time with a hamstring issue but has worked his way back. It's a small sample size, but he owns a 2.87 ERA over his first five starts.
His strikeout rate sits just above 21 percent to start the season. One concern is that he has only thrown 15.2 innings this season and also has not made it through the fifth inning, so that could be a drawback for the Cardinals. At worst, however, he could be a viable rotation option as a potential stopgap until the deadline arrives or could be used in a long relief role.