Really good comments here.
About changing rubber, I think it was maybe 70% psychological and 30% technical. Mentally it really does give me confidence to loop. I know i have at least 3 games coming, he will not loop a single time but push every time to my bh. It really gives me confidence knowing I have a strong hybrid rubber on my bh to go and loop his ball. And 30% technical is that actually there is some real benefit to looping with hybrid. I think this fact is well observed already.
I havent posted video lately, but in the past 8 months or so, i really have been working on looping earlier in the rally. Particularly on looping opponents serve. I would agree with you that this strategy is of particular value. I feel i need to loop the opponent serve to play equal with those 1950 and 2000 players. When I execute it well, then I can genuinely win those matches.
To a lesser degree i have been working on the counter loop. Im much more confident counterlooping away from the table than counterloop near the table. I use the near table counterloop sometime, but i find it hard to practice. I had another thread on this topic.
Finally its interesting that many people in this thread didn't recognize that the problem against 1600 player was maybe 80% psychological and 20% technical. A few did recognize that the problem was more of determination to play your own style and avoid getting into his weird style.
The main thrust of this thread that i wanted to discuss was the experience of totally shutting down. Your body just crumbles and cant execute what you know its capable of. Im sure im not the only one who has done this before. I feel this issue didnt get discussed well and became focused on technical ability of looping underspin.
If simply changing tactics to attack as early as possible caused you to win overwhelmingly, then the tactical aspect cannot be overlooked.
But I do think you have a point that, as you got drawn into longer push rallies, the mental issues were brought to the forefront of your experience in the match and you started falling apart. So, the mental stuff should not be overlooked.
But, having a solid tactical approach (attack as early as possible) would have never let this opponent break you down mentally.

Even though this player does not present a threat of attack, the threat of being drawn into long push rallies where you feel awkward and lose confidence in your attacks is why the tactic of attacking as early as possible took care of the issue.
So, bad tactics lead to your mental game being broken down as you played your opponent's game and were not figuring out how to change the scenario.
Once you changed the tactics, the mind issues, the jedi mind tricks, the stuff that caused you to lose confidence, they never even came up. Hard to separate the two.
One time I watched a high level coach (Damien Provost at the time 2700+ and an excellent coach) working with a friend who was a 2200-2300 level player. They would do training sessions that would last a few hours. At one point in this particular session, Damien put his racket down and yelled in frustration. Then he explained to the player: "you have at least 2400 level technique, BUT your game strategy is 1200 level. You have to stop that and use better tactics."
I think 1200 level tactics was an exaggeration but the player I am talking about did like to mess around and do silly things.
Anyway, I think, often, at least in videos from the past, you have been using tactics that will work on lower level opponents so that you can win without training skills that will help you improve, and without using tactics that would be useful vs higher level players. It sounds like you are now making those changes already. But what got you to break down mentally against this push player is one of those low level tactics where you let the other player mess up instead of taking the initiative right at the outset of each point.
Working on this until it is comfortable will help you find out what your next steps are and will open the door to other aspects of TT technique that you don't yet realize you need to work on:
- If you are playing a good looping player, can you counterloop with that player over and over in a rally where you are both trying to overpower the other.
- If you are playing a decent level chopper, how many of his chops can you loop in a row before you have to push to reset the rally?
(For both of the above, the scenarios would be based on play in an actual match not in training).
When you watch higher level players, they can counterloop over and over even when their opponent is ripping heavy topspin loops at them over and over from high angles. And vs a good chopper, a high level player may choose to loop, then push and loop, then push but they can loop many times in a row when they want.
Last thing, tactical, but requires footwork: if you know that your opponent is going to push long to your BH, stepping over and pivoting to the FH, and looping to the opponent's deep BH (so he can't get you out of position and open on your FH) would be something that should be in your bag of tricks. It is another technique you may not want to use all the time. But if the pattern is that predictable, then doing the footwork to the FH in order to make the player pay with the FH will get inside that player's head.
It is a basic tool. You should have it in your toolkit at the level you are playing at.