Brandon LaFell caught 87 balls and 9 touchdowns in our offense last year, so while you may only consider him a "role player," his role was awfully significant.
The expectations are much, much higher for a proven player who knows our system vs. such no-names as Martin, Dobson, Harper, and Johnson (someone I'm not even familiar with yet). There's not really any comparison whatsoever, and he's been quite underwhelming in his second year here, particularly at a time when he could've acted as a proven, veteran leader.