Let's set up a fake fanbase war! All you have to do is decide whether Jason Mraz is a downgrade from Justin Bieber as a Taylor Swift duet partner from Los Angeles or vice versa. Be insistent in your opinions. Invoke autotune and John Mayer. Try not to imagine what other purposes the phrase "autotune and John Mayer" could be used for.
Also notable: this is a case where it's in fact OK to say Jason Mraz surprised the audience! We have video evidence that at least one person was surprised, at least if "OH MY GOD, DON'T TELL ME HE'S COMING, DON'T TELL ME HE'S COMING!" counts as surprise and not fervent anticipation.