He played for Ginebra San Miguel from 1986 to 1991 and 1994 to 1995. In his rookie season in 1986, he helped Ginebra win its first ever championship during the 1986 PBA Open Conference. He earned his spot in coach Robert Jaworski's rotation as a reliable backcourt defender and his valuable contributions on defense helped the Gin Kings win two more championships in 1988 and 1991.[2]
He retired from playing in the PBA after the 1995 season.
Coaching career
Philippine Basketball League
He once mentored teams such as Dr. J. Alcohol / Ana Water Dispenser, Boom Laundry Masters, Montaña Jewels, Blu All Purpose Detergent Kings, and Noosa Shoe Stars. In 1998, while coaching for Doctor J, he won his first ever championship as a coach at the expense of the heavily favored Tanduay team in the 1998–99 2nd PBL Centennial Cup.
Mapua Cardinals
Isaac took over as Mapua's head coach prior to the 2007 season.[4] He led the Cardinals to back-to-back Final 4 slots wherein during both appearances they were at #4. His records with them were 6–6 and 9–5, respectively.
He led them to several titles including the NCRAA championship in 2007.[6] After a season coaching Red Bull, in 2010 he once again coached the Chiefs, this time, in the NCAA for two seasons.
In 2014, Isaac was retained as the team's head coach after team owner Dioceldo Sy elevated his franchise as an expansion team in the PBA. He is expected to inject the "never-say-die" experience that he got from his playing years with Ginebra. However, his team was winless in the Philippine Cup, with 0–11 win–loss record.[9] In his first season with the Elite, he compiled a 6–27 win–loss record.