From what I've been reading (and seeing in photos), Sainz is known to athletes as having a less-than-professional demeanor compared to other journalists. When I say "professional", I really mean "American professional" when speaking of journalism.
Sainz, herself, said she didn't really deem the catcalls offensive and if I'm a betting man, the players who did it probably were comfortable doing so knowing her personality. Not really sure how Mexican female sports reporters (especially at TV Azteca) go about their business, but Sainz' perspective is a bit different than the female reporter who was offended. There's a definite way to behave within American work place environments- and having been around the world, I can say journalism is one industry that diverges widely in several aspects (including content, bias, professionalism, etc).
I'm not saying catcalls are acceptable in a work place, but there's a gray area when it comes to this particular journalist. I don't know of any serious female reporter who measures body parts with a tape, who wears midriffs during an interview or happily lets a player lift her up. I think Sainz was treated differently than an Erin Andrews or Michelle Beadle for a reason.