Former Ajax boss de Boer was given his marching orders after just four games of the Premier League campaign following a 1-0 loss at the hands of Burnley.
Roy Hodgson was given the task of replacing the Dutchman but has still been unable to pick up a single point in the league in his three games at the helm.
Ronald de Boer has not been impressed with the Eagles’ decision and feels his brother should have been given more time to get his philosophy across to the players.
He told BeInSPORT: “It hurts, definitely. He’s a winner and he worked so hard at Crystal Palace to get it going. Finally, when he thought there was a light at the end of the tunnel he got sacked so that hurts even more.
“He has to stand up again. He’s still hungry to coach another team but for sure it was a knock down.
“We just started, that’s why it’s so ridiculous [to be sacked] after four games. They played a good game against Burnley.
“You thought they’d begun to understand a little bit the philosophy, the way. It takes time.”
Manchester United are ready to launch a straight £60million bid to try and sign Chelsea star Willian, reports have claimed.
Liverpool are being linked with a swoop for Inter Milan striker Andrea Pinamonti, but have been warned he wants regular action.
Borussia Dortmund are reported to have dropped all interest in Chelsea striker Michy Batshuayi and are looking elsewhere.
Sevilla are bracing themselves for interest in Steven Nzonzi and have lined up a replacement in the form of Marcos Llorente.
Newcastle are targeting a move for Juventus midfielder Stefan Sturaro and are reported to have lodged an opening bid of £11.5million.
Southampton have joined the race to sign Norwich midfielder James Maddison, but will have to move quickly to secure his signing.
Bournemouth are weighing up a move for Sheffield United midfielder David Brooks, but will have to pay £12million to land him.