With 20 minutes left in front of a home crowd, he found himself on the receiving end of a one-sided and intense halftime speech from Tom Izzo.
"The majority of it," Appling said of how much was focused on him. "He told me I wasn't playing well on either side of the ball and I just wanted to come out in the second half and respond.
"I picked up my energy level and my defensive intensity and it kind of trickled down to all the other guys and that's what kind of changed the game for us."
The senior showed up just in time on his senior day, hitting a pair of 3-pointers and scoring 12 points in the second half of the Spartans' 86-76 win against Iowa on Thursday.
"At halftime, we definitely challenged Keith," Izzo said. "Keith Appling the first half to the second half was Keith Appling the last six weeks to Keith Appling the first six weeks."
Stuck in a shooting slump brought on a by a wrist injury that had him sidelined for three games, Appling hadn't seen a 3-pointer go through the hoop since the first meeting with Iowa on Jan. 28 in Iowa City.
"When the head dies, the body goes," Izzo said of his point guard's importance. "The head had been a little knocked unconscious for a couple weeks."
It woke up and broke out of the slump in the second half and brought the Michigan State crowd to its feet. His first 3-pointer went through with 15:07 to go after a made attempt earlier didn't count because it came after a whistle.
"He hit that one, and I looked up, and people in the upper deck were rising," Izzo said. "I told that to Keith as we walked off the floor. ‘Every person in this building had your back.'"
"I feel like it was really more so confidence," Appling said. "I just wanted to get a lot more comfortable with my hand.
"I feel like I kind of got over that lump this week in practice and it just carried over to tonight in the second half."
Iowa closed the first half on a 14-6 run as Devyn Marble posted 16 of his game-high 24 and the Hawkeyes led 41-39 at halftime.
A 9-0 Michigan State run in the first 3:58 of the second half erased that. Appling had five points in that stretch and eight of the first 14 in the second half as the Spartans started to open up a game that featured 12 lead changes in the first half.
Iowa came right back to pull within 53-51, but the Spartans bench players stepped up big. A 15-4 run – keyed by eight straight points from Travis Trice to cap it – gave Michigan State a 68-55 lead.
"That was big because at that point in the game, it was neck and neck," Trice said. "That was big for us having a bunch of bench guys in and going on the run."
Trice finished with 17 points on just five field-goal attempts and hitting three of the Spartans' 10 3-pointers. As a team, the Spartans shot 58.3 percent, good for the second-highest mark this season.
Senior Adreian Payne had 14 points and four rebounds.
"I feel like we kind of are getting it all back together now," Appling said.
The win ensured the Spartans of a first-round bye in the Big Ten Tournament in Indianapolis as they enter their final regular-season game at Ohio State on Sunday.
"The way we see it is we've gotta win 10 more to win it all," Trice said. "It's just another game and another team that's in the way of our main goal so we gotta get on a winning streak."