Christian Horner believes that Daniel Ricciardo is showing signs of returning to the calibre of Formula 1 driver that had left Red Bull in 2018. Following his departure from McLaren at the end of last season, Ricciardo elected to take on a 'third driver' role at Red Bull in order to take a break from racing. It's the first F1 season without Ricciardo in eleven years, and the popular Australian is has been tackling simulator work and promotional activities for the team so far this year. When asked about Ricciardo's progress since joining the team, Red Bull Team Principal Christian…