Although Johnson admits the appointment of the German boss has been "good" for the club, he believes the Chelsea players must "have a look at themselves" as they should have been performing to the same level under Frank Lampard.
Speaking to CheltenhamGuides.com, Johnson said: "When Tuchel first came in, Chelsea were beating teams that they should have been beating, but now they've shown they can beat Tottenham, Everton and got a good result against Manchester United.
"I think that Lampard could have done a similar job, it's just a shame and a problem for the players, how can they perform like this for the new manager but they couldn't for Lampard?
"So the players have to look at themselves. But that said, right now the appointment looks good because they're absolutely flying."