There are only two reasons that a judge gets reversed that much. Either s/he doesn't understand the law, or else refuses to apply it correctly. It's hard to believe that Judge Sotomayor truly couldn't figure out the law in each of these cases. Instead, her high reversal rate suggests a willingness-- like that manifested by the oft-reversed Ninth Circuit -- to use the law as an instrument to make policy.
It's worth pointing out that, as a justice, she'll have the chance to do successfully what she apparently tried to do before -- make law from the bench. There is nothing to constrain a Supreme Court justice in his or her work but an internal commitment to upholding the rule of law -- which means (among other things) pledging impartiality toward litigants, and realizing that the work of judges (even those on the Supreme Court) is supposed to be to interpret the law as it is written, not to rewrite it so as to make it more to their personal liking.