As I understand it, those records did not pass 10mil sales (Diamond status) until 1996 (vh) and 1999 (1984).... released in 1978 and 1984.
Contrast that with Appetite for destruction, released in 1987 and achieved diamond in 1993. Its easy to say which version of guns drove those sales.in the case of 1984, according to the riaa website, half of the album sale for 1984 were generated after sammy Joined, coincidentally its the same for VH, half of record sales occurred after Sammy joined. Not saying they bought them for Sammy but the RIAA data makes it pretty clear they sold way mre records with Sammy in the band than with DLR...
Perhaps its blasphemy, but without Sammy Hagar, I think Van Halen is only relevant to people who play guitar, or those who still aqua net their bangs... Sammy helped keep them in the limelight and drove the volume of total catalog record sales to the larger mainstream audience.