"I'm very, very surprised with the news that Eddie Howe is leaving Newcastle," Shearer told Betfair. "I guess it's strange timing with three weeks to go until the new season kicks off. I don't know what's gone on, whether it was the end of last season, whether it was the summer, whether he feels they can't continue to sell his best players.
"I'm led to believe it was Eddie's decision to leave."
He added that the timing left little room for the club to prepare: "If something was going to happen, you would have thought it would have happened at the end of last season so it would have given Newcastle time to prepare."
The Newcastle United legend was blunt about how the club's transfer business looks from the outside amid Howe's exit.
"I don't think it's a great look for what's happening at the minute with Newcastle. We're selling all our best players. The fans are seeing Isak go, the fans are seeing Tonali go, the fans are seeing Gordon go. My guess is it's probably only a matter of time before Bruno goes," he said, predicting Bruno Guimarães could follow Alexander Isak, Sandro Tonali and Anthony Gordon out of St James' Park.
Despite his confusion over the exit, Shearer was effusive in his praise for Howe's five years in charge, singling out Newcastle's Carabao Cup final win over Liverpool at Wembley last season — the club's first major trophy since 1955.
"He gave me my best day as a Newcastle fan with that day at Wembley. He's given us some incredible nights in the Champions League that we'll never forget. He did a wonderful job for Newcastle, so it's a huge thank you to Eddie," Shearer said, recalling how Howe inherited a team just above the relegation zone in November 2021 before steering them to 11th place that season and, eventually, Champions League qualification.
On Howe's likely successor, Al-Ahli's Matthias Jaissle, Shearer was more cautious.
"Clearly, he's got a great record in Saudi. Clearly, he's very young and inexperienced. The Premier League is a beast of a league. It's a big ask for anyone to come in and take over after what Eddie's done. If Jaissle does come in, you're asking a 38-year-old to navigate very, very tricky waters," he said.
Shearer added that Howe would have no shortage of offers once he decided on his next move, and urged Newcastle to balance their pursuit of young talent with proven experience.
"I'd like to see Newcastle sign players, because it's alright having this bold new look of going for young, hungry players who are 30 or 40 million pounds. But also, the Premier League is tough. You need some experienced heads in there as well. There's no doubt this season's going to be a tough one for Newcastle. You can't keep selling your best players in the hope that you're going to get to where you want to get to. What I would like is stability," he said.