Mendiguren's best years were from 1988 to 1990, as he totalled 63 league matches for the Basque side (54 starts) whilst scoring 14 goals, with the team finishing seventh and 12th respectively; in subsequent seasons, he returned to his role as a bench player, but still managed to be used regularly.
In the 1994–95 UEFA Cup, Mendiguren contributed six appearances as Athletic reached the third round, starting in both legs against Newcastle United (his side advanced on the away goals rule, 3–3 on aggregate).[3][4] He amassed competitive totals of 223 games and 23 goals during his spell at the San Mamés Stadium.[5][1]
^Castañeda, Eduardo (2 November 1994). "El Athletic pasa por coraje" [Athletic go through due to guts]. Mundo Deportivo (in Spanish). Retrieved 23 August 2022.
^Zubieta, Jon (23 December 2019). "Beñat le pisa los talones a Zubizarreta" [Beñat hot on Zubizarreta's heels]. Mundo Deportivo (in Spanish). Retrieved 13 September 2023.