One of Joshua Zirkzee’s former Bologna teammates has been paying tribute to the new Manchester United signing. Serie A may no longer be the first-choice destination for the world’s greatest number nines – unlike the 1990s – but Italy’s top flight is still home to plenty of elite-level frontmen. Yet, according to a former Bologna team-mate who watched his development with a keen eye, Manchester United’s first summer signing still stood out head and shoulders above the rest. Joshua Zirkzee may not have scored as many goals as Olivier Giroud, Dusan Vlahovic or the briefly-United linked Victor Osi…