It would be "madness" if Ferrari pushed Sebastian Vettel out, according to Jenson Button, who thinks Carlos Sainz may not provide a trouble-free replacement.
Ferrari announced last week their relationship with Vettel would not continue beyond the 2020 season after failing to reach an agreement over a contract extension.
Reports have suggested the Scuderia did not even offer the four-time champion a new deal.
Button would be baffled if that was the case, suggesting it would even be an odd decision if they simply wanted to pave the way for Charles Leclerc to lead the team.
"If he was pushed, for me it's madness. A four-time world champion," Button said on Sky Sports.
"I think he showed his speed last year. He had a tough moment in the season when Charles was performing really well and I think that hurt him a little bit mentally. But he came back really strong, and he's just somebody you would definitely choose to put in your car if you had an F1 team.
"There must be more to it. I don't know if Ferrari are going down the route of not wanting two number one drivers or what but it's a really strange choice for me and I'm still shocked that Sebastian [won't be] in a red car."
Sainz, who finished sixth in the drivers' standings last season, will arrive from McLaren to fill the seat vacated by Vettel.
Having shown significant improvement in 2019 and earned a first podium at the previous Brazilian Grand Prix, Button does not expect Sainz to be content operating as a number two driver.
The 2009 Formula One champion also claimed that had the season not been delayed by the coronavirus pandemic, Vettel could have done enough to earn an extension by this point.
"If [Ferrari team principal Mattia] Binotto has gone for Carlos because he thinks he's a good pair of hands but won't really give Charles a run for his money, then I think he's mistaken," said Button.
"I think Carlos is a winner, he's like his father. He wants to bring home a championship. So [Binotto] has chosen the wrong person if he just wants a good atmosphere.
"We'll have to see how it plays out, but it's just a weird time at the moment. We've not seen an F1 car in months and to make driver choices at a point when drivers haven't been driving is really unusual.
"Normally it's mid-season and you see how the guys are performing in that year. Vettel could have been four, five wins in at this point in time and then I'm sure the decision would have been very different."