Both are box to box midfield players, a type of player which until Guardiola signed Vidal didn't think was in his thinking to go for.
Guardiola did not seem to be responsible for that transfer.
The background to this transfer: Bayern's chief scout Reschke was scout of Leverkusen before and brought Vidal from Chile to Germany some years ago. The sale three years ago from Leverkusen to Bayern did not work out because Leverkusen did not want to sell - but then sold to Juve. Now that Reschke is working for Bayern they made the buy.