Bayer Leverkusen started the pre-season with diagnostics on Sunday, back in action from a Bundesliga and German Cup double they achieved in historic fashion last term. Xabi Alonso’s men became the first German team to go unbeaten all season in domestic action. They lost only once in 53 matches in all competitions, missing an unbeaten treble due to a 3-0 Europa League final defeat against Italy’s Atalanta. “The coach said we can do things better, two titles are not enough,” goalkeeper and captain Lukas Hradecky quipped in a club TV video published on Sunday. He added on a more serious note: “It…