This is based on what? Lauzon looked tentative his first few games and then settled in. Zboril is still in the first few games stage of his NHL development.
According to Mark Divver (who is very good), and who covers the team, he thought Zboril should have been called up before Lauzon, based on their AHL play this year. You may be forgetting that Zboril suffered a concussion in China after the high/late hit by Hathaway and may not even be 100% back yet?
Clearly the bruins FO didn't agree. Lauzon had a better start in a small sample size , until he also got injured.