Two more items maybe worth a thought --
First, unless you must be there for the first pitch, be willing to arrive a little late and the traffic will be easier. People try and pour out early on fridays, which means the later u can wait the more of downtown that will be cleared out
Second, as you come in 59, be willing to exit before you get to the 288 merge.
There is a "Spur 527" exit -- which kicks you out pointing directly at downtown. From there, you can take Travis north (San Jacinto is even better but is over ~3-4 blocks) straight into downtown until you are parallel to MMP, which will be on your right (to the east). Going this way will save you at least 10 minutes, perhaps more.
If you do not have a parking pass, I prefer parking on the north side of the stadium.
If you do have a pass, it is likely for the lot just east of the ballpark, just east of 59 (which is elevated beside the stadium)
Have fun!