Francis, who was picked up by the Dolphins two years ago as an undrafted free agent, hasn't played with Diggs since 2012. But Diggs obviously made quite an impression.
Considering Diggs' place in the long line of standout wide receivers in the 2015 draft class isn't anywhere near the front, that's either an incredibly bold statement about Diggs, or incredibly dismissive about the Dolphins' roster. Give Francis the benefit of the doubt, given the setting of where the remark was made (Francis was at Maryland's pro day in support of former teammates).
Context is always important, but Francis obviously remembers Diggs' freshman season with plenty of reverence. It was arguably Diggs' best season at the college level (54 catches, 848 yards, six touchdowns) -- not exactly dazzling numbers, but they were enough to be the team's runaway receiving leader as a first-year player.