Who knows what kind of back-room deals go down. Berto might have a sweet contract that allows him to get a free ride (just a guess). Martinez came to the party late in his career, so he might not have much leverage.
Berto definitely has deals. It's common practice for HBO to extend opportunities to unproven talents from time to time to try to get a jump on what they perceive to be future stars; at the same time HBO start showing Berto they were also showing Angulo and Kirkland with a degree of frequency. HBO's invested in Chad Dawson, but it's kind of backfired because he hasn't attracted viewers or been a big draw. Martinez should have some leverage as Maravilla-Williams II had the second highest ratings of the year to Cotto-Foreman.