Donald Trump himself has demonstrated willingness to use bribery and sharp practices to get ahead in business, and members of his transition team are no better, with members such as Chris Christie. His transition team includes politicians and Washington insiders, not much different in composition from the previous administration. There's no reason to expect more or less corruption than is usual in Washington.
I do not know much about Trump's transition team, neither do I know much about the previous administration or how corrupt it was. However, I do know that there is no administration in the world that doesn't have some form of corruptness or the other. Therefore, if Trump says his transition team is corrupt, I believe they are.
Trump's promise to the voters in his party was to "drain the swamp" by replacing politicians entrenched in Washington, with outsiders, who wouldn't work within the system. Right now the news about his transition team shows that he is hiring politicians with years of experience in Washington, who are coming from the system he promised to essentially reboot. He is changing nothing.
In 4 years Trump will come back and campaign on clearing the swamp and his supporters will believe him again. Politics is about taking advantage of people. It's a game we fall for every election cycle. He's a businessman interviewing candidates for open positions; shouldn't we wait to see who he selects before complaining?