The line is strong but underbluffed; solver wants the river call with 99, yet folding versus NL200 tendencies is very defensible.
Facing the small donk on this low, connected board, calling with an overpair is exactly what the solver wants — we protect our range, keep in all the weaker pairs and bluffs, and avoid blowing up the pot versus a range that still has plenty of strong hands.
Calling turn with overpair + gutshot versus this sizing is again the correct play; we still sit in the upper-middle of our range, have good equity, and raising would isolate us against two pair+ while folding would be giving up too much.
Solver wants us to bluff-catch here a lot with 99, but folding in practice versus the typical NL200 population is quite reasonable given how strong this line is and how underbluffed it tends to be. **Ranges:** After donk-bet flop / bet turn / big river bet on this runout, CO’s value range is JJ, 88, 77, some 55/44, a few Jx8x/J7s/87s-type two pairs, plus the occasional T9/96 that got there — that’s a very value-heavy shape. Our hand is now just second pair, no straight, so it functions purely as a bluff-catcher. **Math:** Pot is ~123BB, facing 78.3BB, so we’re getting ~1.6:1 and need about 39% equity. Solver thinks 99 clears that bar in theory because CO should still have enough missed draws and thin value/bluffs; versus a more value-heavy, underbluffed range, our real equity drops well below that threshold. **Exploits:** At NL200, players rarely take the tiny-donk / bet / large river line as a bluff often enough — they arrive at the river underbluffing after investing on two earlier streets. Exploitatively, overfolding second pair in this configuration prints money versus the pool, even if the solver mixes more calls. --- > **Takeaway:** In theory 99 is often a call here, but at NL200 a big river bet after flop/turn aggression from OOP on this texture is underbluffed enough that folding second pair is a solid exploit.
Note: From a pure GTO standpoint, 99 should mostly call the river given the pot odds; folding slightly overfolds our range and gives up some theoretical EV.