DougDFC first off thanks for posting your matchplay I love watching matchplay. Also, it is brave to post knowing you are going to get picked apart and I have the utmost respect to those that post for critique rather than do not post and cry about balance etc. Thats the last of my kind words.
1. If you hit d2 I think you can combo to mb swamp hands and go for reset this would truly have made you win against this flash if you did that alone.
2. Your approach as a whole is one dimensional and he could read it. You didn't make him fear waking up, yes he can wakeup attack but you need to give him a reason to.
3. Get your back to wall WC mb combos down. They hurt a lot and you WILL be cornered by Flash often.
4. MB Trait does tons of damage since it is unscaled and gives you ability to buff.
5. Goto wiki data and know when you can attack. Also if there is a gap by 3 frames you can back dash pretty easily as Grundy.You respected him way too much and disrespected B22 flash frame trap too much.
6. MB cleaver is very good way to get the heat off of you. Armor, combo, safe +3.
7. Grundy works on trading damage and doing more, just remember typically you WILL do more damage then Flash on average since your trait is available anytime.
8. Manage meter better, you sit on over 2 bars for most of your games.
9. Practice interact setups and dealing with them, you looked very awkward on most stages.
10. Also you should pretty much YOLO d2 trait most times since you will be punished trying to block after a blocked d2.
Have faith in Grundy, it is only a matter of time before people realize how sick this character is.