VanGennip just had tied the game with a hard-earned basket inside and was fouled by Naylor standout Kendal Rodgers.
The foul was the fifth on Rodgers, who was forced to leave the game after scoring a team-high 16 points.
VanGennip's free-throw attempt missed, and the Bobcats would not score again in a 55-50 loss Tuesday night.
"You hate to see it end at any time," a despondent Delta coach Randy White said. "It doesn't matter where or under what circumstances, you just hate for your season to end. You'd like to keep it going. We had our opportunities. We just didn't come out ahead."
It was in the quarterfinal round where Naylor ended Delta's season a year ago with a 42-37 victory.
Delta trailed by as many as nine points Tuesday. The Bobcats missed nine consecutive shots from the floor in the middle of the second quarter, which allowed the Eagles to jump out to a 27-18 advantage.
"We just had an off night, I guess," Delta senior Samantha Bartels said. "I could tell when we was warming up I wasn't on. I don't know about anybody else."
Delta was 20 of 58 (34 percent) from the field and made just 1 of 17 (6 percent) from 3-point range.
Delta stayed within reach despite its shooting woes and the foul trouble of junior Tori Burton.
Burton left the game after picking up her third foul with 6:56 left in the second quarter and did not return until after halftime. She then picked up her fourth foul with 7:19 to go in the third quarter and sat out the rest of the period.
"Huge," White said when asked about the impact of Burton's absence. "Tori is one of our three leading scorers. She is our leading rebounder. She is our leading free-throw shooter."
VanGennip, who led all scorers with 22 points, regularly worked her way inside during the game to help keep the Bobcats close.
Delta trailed by six points entering the fourth quarter but forced turnovers on three consecutive Naylor possession with less than four minutes left in the game, which led to a 7-0 run capped by VanGennip's tying basket.
Bartels finished her high school career with 15 points.
The Bobcats finished the season 17-10.
"I don't know," VanGennip said with tears in her eyes. "It was our off night. It was a bad night to have an off night."
DELTA (50) -- Rachel Bartels 6, Machela VanGennip 22, Macey Parks 2, Tori Burton 5, Samantha Bartels 15. FG 20, FT 9-13, F 16. (3-pointers: Burton 1. Fouled out: none)
NAYLOR (55) -- Taylor Day 7, Andrea Sullivan 7, Rachel Morris 2, Ericka Engelman 9, Holly Deckard 14, Kendal Rodgers 16. FG 18, FT 12-24, F 13. (3-pointers: Day 2, Sullivan 2, Engelman 1, Deckard 2. Fouled out: Rodgers)