Jackson, which went 8-32 during the regular season, won its first two games at the Missouri Senior Babe Ruth state tournament.
But Jackson was bounced from the nine-team, double-elimination event with a pair of losses Tuesday to end its season with a third-place tournament finish.
"I'm proud of third," Jackson coach Tracy Wyatt said. "Everybody thought we'd be a pushover here. We proved we weren't. They've come together. They've shown they can play together as a team during this tournament."
Jackson entered Tuesday afternoon's winners bracket final at Hillhouse Park as one of just two squads without a tournament loss.
"To stay in the winners bracket is huge," Poplar Bluff coach Jeff Null said.
Tournament host and defending state champion Charleston then eliminated Jackson 11-5 in Tuesday night's losers bracket final.
The Fighting Squirrels (26-23) need to beat Poplar Bluff twice today to claim the crown and earn a regional berth.
"We're still kicking," Charleston coach Michael Minner said.
"We just didn't get the clutch hit," said Wyatt, whose squad had only six hits but received eight walks and a hit batter. "Give their pitchers credit. Poplar Bluff is an extremely good team. It takes a real good game to beat them."
Jon Winkler took the loss despite pitching well. He allowed nine hits and was charged with eight runs, all earned, over 5 1/3 innings. He struck out two and walked three.
"I think I pitched pretty well," Winkler said. "They got some lucky bunts that one inning. They strung runs together."
The inning Winkler referred to was the third, when Poplar Bluff broke a scoreless tie with four runs on five hits and two of Winkler's three walks in the game. Both free passes in the frame came with the bases loaded.
"Overall he did pitch real well," Wyatt said about Winkler. "This is three times in a row he's been good against Bluff."
A bunt also haunted Jackson during Poplar Bluff's two-run fifth inning that made it 6-1. After a leadoff walk, Jackson failed to record an out on a sacrifice bunt that went as a fielder's choice. Jackson's first error of the game also hurt when Alex Lewis followed with a two-RBI single.
Winkler's pop-fly RBI single in the fourth inning got Jackson on the scoreboard.
Ross Moldenhauer drew a bases-loaded walk in the sixth inning to pull Jackson within 6-2.
The Thunder added two insurance runs in the bottom of the sixth to go up 8-2 before Trent Steffens' RBI ground out in the seventh inning rounded out the scoring.
"We left runners on base. That hurts your momentum," Winkler said.
Winkler and Steffens both had two hits for Jackson. Lewis paced the Thunder, who had 11 hits, with two hits and three RBIs.
Lucas Tibbs pitched five innings for the win. He allowed six hits and two runs. Two more hurlers finished with an inning apiece.
"Our pitchers really weren't very sharp, but they seemed to make a pitch when they needed to," Null said. "They were gritty."
Jackson then was eliminated with the loss to Charleston. The Squirrels avenged a setback to Jackson in their second tournament game.
Charleston, which is 5-1 in the tournament and has won four straight, including a pair Tuesday, took advantage of six Jackson errors to score seven unearned runs.
"Our defense hurt us," Wyatt said.
The Squirrels went ahead for good with two runs in the bottom of the first inning. They got RBI doubles from Ryan Fortner and Tim Hillis.
Charleston put Jackson in a deep hole with five runs on just two hits in the second inning. Four of the runs were unearned thanks to three errors.
Jackson could not recover from that early 7-0 deficit, although Wyatt's squad made things interesting for a while.
Jackson, which trailed 8-1, cut the deficit to 8-5 with four runs in the fifth inning when the team recorded four of its six hits in the game. Josh Douglas and Colby Brown had RBI singles.
But that was it for Jackson's offense, and Charleston iced the victory in the bottom of the fifth with three more unearned runs.
Chris Hartle suffered the loss. He allowed seven runs, three earned, and four hits over 1 2/3 innings. He walked four.
Cory Devenport was solid in relief. He gave up four runs, one earned, and six hits over 3 2/3 innings.
Dalton Golightly pitched five innings for the win. He allowed six hits and five runs. Zac Chasteen finished with two hitless innings.
Fortner and Jacob Wilson both delivered two of Charleston's 10 hits. Trey Watkins had an inside-the-park home run.