The Spanish forward joined the Grecians in May 2011, after leaving Northampton. He began his career with Mallorca B before joining Espanyol B in the Spanish second division.In the summer of 2007 he was signed by Roberto Martinez at Swansea City, going on to play for 3 seasons at the Welsh club. In 2010 he signed for Hereford United, but in 2011 he moved to Northampton Town.
Bauza, more commonly known by his nickname Bussy, won the Under 16's European Championships with Spain, playing all 6 games alongside Fernando Torres. He also represented Spain at Under 17 and Under 19 levels, again playing alongside the Euro 2012 top goalscorer.
When joining the Grecians Guillem said "I think I am an attacking player - a striker, second striker or attacking midfielder. I like scoring goals but I am also a team player and I like to think I am a clever player, getting into nice positions for the team. I think I can make any team a little bit better and score some good goals." Guillem started the 2011/12 season very strongly, scoring two goals and putting in some impressive displays. Unfortunately the rest of the season was badly hampered by injuries.