If your thinking of going to Minute Maid park after the Astros game, it is not really worth it.
Too much traffic, not enough surging. Sure, it is a good place to grab a couple of rides on the weekdays, since there is not really much going on in town, but be prepared to take those at regular price.
Why does surging not occur? Because baseball games are soo long, that people usually trickle in and trickle constantly through out the game, so there is never a time of "High Demand". Not to mention, the majority of riders who would take Uber on a regular night, are also with their kids and families, so they end up driving.
As stated above, police shut down the streets for 20 min. This creates a nightmare trying to pickup a rider, so it is best to go before the games end.
Also, the handful of people I have picked up from Minute Maid (after Astros games) usually end up being in the loop, not long distance fares.
Now, I understand you want rides and are probably not focused on surging, and you don't need to be to make Uber profitable, but I wouldn't go after the 8th inning because of traffic. At 15 cents a minute - minus 20% it is not worth waiting in traffic. You can keep track of the game on Google. Just type in "Houston Astros" during the game, and the score will pop up as well as the innings. This works on all major sports. Simply refresh that window for a update.
Now, sometimes surge does occur after the game, but remember, Minute Maid park is in the Downtown/Midtown zone. So you do not need to catch a ride from Minute Maid Park to get the same ride. (avoiding traffic). I know I am the biggest advocate of "not chasing surge". but I have found myself within a few minutes on Washington and simply crossed the surge border within a couple of minutes, and immediately got a ping from around Minute Maid Park on surge). It was a low surge, I think a 2.1, but I took it of course. Remember, Washington turns into Franklin and you are within arms length of Minute Maid Park.