Questions about EV concept and calculations

If I take another scenario where the BU calls a lot more than needed.

Say he calls 80% of the times now instead of 67% that he should.

CO has a perfectly polorized range so his 100% equity hands always win and his 0% equity hands always lose. The CO doesn't adjust his strategy.

EV for CO

Case 1:

Again BU folds, CO wins $100. This happens only 20% of the times now.

EV1=$20

Case 2:
BU calls and loses, CO wins $150

EV2=150(0.80)0.75)=$90

I'm assuming the CO still wins only 75% of the times since he didn't change his strategy and he will still win 75% of the times and lose 25% of the times.

Similarly,

Case 3:

BU calls and wins, CO loses 50

EV3=(-50)(0.80)(0.25)
=-$10

The freaking EV is again +20+90-10=$100

I calculated the EV for BU as well in this scenario and same thing he got EV of $0.

So does BU's calling frequency not matter if the CO doesn't change his strategy? do they still win the same? I assumed that now that the BU was calling more than needed he would definitely lose more EV as its not optimal anymore?

If the CO was to change his strategy against this guy I suspect he would, lets see, change the value:bluff ratio or his bet size.

Changes bet size:

He starts to bet $75 instead of $50.

EV for CO

I'm gonna keep the cases same. Case 1: BU folds, Case 2: BU calls and loses, Case 3: BU calls and wins

Case 1:
EV=0.20x100=$20

Case 2:
EV=0.80x0.75x175=$105

Case 3:
EV=0.80x0.25x(-75)=-$15

EV=EV1+EV2+EV3=20+105-15=$110

Viola, CO starts to win more. I did the same calculations for calculating EV of BU, got his EV of -$10.

So I guess this is how CO can deviate from his strategy and start to exploit BU and increase his EV.

I'm sure same type of calculations for a different change in strategy as in changing the value:bluff ratio can also increase CO's EV.

So let me get this right? CO's EV remains the same no matter what strategy BU uses and CO can improve or reduce his EV by changing his strategy as the BU changes his? Cause vs same BU player a bet size of $20 instead of $75 or $50 led to CO's EV becoming $88 which is worse than the EV of$100 that he had had he not changed his strategy at all after the BU changed his.

To OP:

In EV calc for CO, don't include value bets. He is supposed to be BE on his bluffs. The calculation for BU is prolly correct, he is is supposed to be BE on his bluff catching.

To maheepsangari:

Same thing.

If both play according to GTO, then either one can change their strategy (but not both) without shit happening. But the one that does become exploitable in the obvious way.