Leeds spent the first half of the campaign competing in the top half of the Championship table but the Yorkshire giants now sit in 13th place, 11 points adrift of the playoffs.
Radrizzani has been criticised for not showing as much ambition as some of their rivals, but the Italian has laid the blame at the feet of the club's under-performing first-team squad.
"We have given them everything possible to just focus on the football. As a club we support them in everything - we gave them long-term contracts, we supported them going to a mid-season camp in Spain," Radrizzani told talkSPORT.
"We did everything they wanted, but we didn't get back their commitment, passion and the spirit, particularly in the last game, the most important game against Middlesbrough away and we played very poorly.
"For me, that was the bottom of the season because there was no commitment, no passion and no spirit. I don't want players in my team and representing Leeds United with this behaviour, so I hope they can learn and will be here with me next year playing better and with more commitment."
Since the start of 2018, Leeds have won just one of their 13 matches in all competitions.