One might argue that he should have been more aggressive in purchasing other IP portfolios - maybe Nortel (although that may have been before he was at Google) and Sun of course.

But Motorola gave Google exactly what it needed - a mature patent portfolio which other companies would have to cross license.

The Nortel patent portfolio sold for $4.5 billion, which was higher than Google was willing to pay.

Andy Rubin did not like what Samsung was doing with Android and wanted a captive OEM. This doubled Google's headcount, it changed Google's financial numbers materially, it cost a fuckton of money even at Google scale at a time when it was apparent that no phone OEMs were very profitable, and it was strategically incoherent.

Andy Rubin was exactly the right guy to make Android a success. But buying Motorola and intending to keep it as a captive OEM was a large mistake.