In the first, Arendt yielded a leadoff walk to Tyler Ulrich, who came around to score.
Arendt ran into more trouble in the third when he hit Brian Danner with one out, then gave up a pair of two-out RBI singles to fall behind, 3-0.
"We thought Chris was the guy, but he didn't have his best stuff," Chandler said. "A couple of 0-2 counts went for hits, hit batters. ... That's baseball."
Minnich entered the game in the fourth, but didn't fair much better. In the fifth, he allowed seven of the first eight batters to reach base safely, part of a three-run inning for Red Land.
The Patriots came back for more in the sixth on Chris Young's leadoff double, then a one-out RBI single by Skyler Hunt for a 7-1 lead. Hunt finished with three hits and three RBI.
"Coming into the year, we knew Skyler would be our best defensively, but we didn't know what to expect offensively," Red Land coach Kyle Wagner said. "He has been a big bat for us."
Meanwhile, Red Land starter Kyle Otstot plowed through the Waynesboro lineup, allowing only two hits, walking six and striking out five in a complete-game effort.
"We were hoping to get an excellent effort from Kyle," Wagner said. "We gave him 15 or 16 days' rest after clinching the (Commonwealth) division."
Otstot certainly looked like a well-rested pitcher, limiting the scoring opportunities for the Indians, who entered averaging 10.3 runs per game.
Waynesboro (18-5) got on the board in the third inning, courtesy of Arendt's RBI groundout that scored Mitch Walck.
In the sixth, Nathan Minnich led off with a triple that fell just shy of the 420-foot marker in left center. He scored on Zach Helman's groundout.
Waynesboro mounted its biggest scoring threat in the seventh. With two outs, Brenton Kopecek walked and Arendt and Nathan Minnich were hit by pitches to load the bases. Kopecek and Arendt scored when Jamison Walck reached on an error.
However, after a walk re-loaded the bases, Otstot struck out Matt Anderson to end the game.
It was a bitter end to another solid season for the Indians.
"The guys had a great season," Chandler said. "(The seniors) have had great careers."