Before Diggs and Bland, the still active player with the most INT's for the Cowboys was Anthony Brown with 9. It took six seasons to accumulate those 9 INT's.
Both Diggs and Bland passed him by in their 2nd seasons.
In fact, if you only look at their first two seasons, the Cowboy with the most INT's is Everson Walls. He got 11 in his rookie season and 7 in his 2nd season.
2nd place is Trevon Diggs with 14
3rd place is Daron Bland with 11
Another prominent name on that list is Michael Downs with 8. He and Everson Walls were the two rookies along with Dennis Thurman and Charlie Waters, to set the Cowboys record for most INT's in a season. Their total still stands as 3rd best in NFL history. They were nicknamed Thurman's Thieves.
What I'm saying is that when Diggs comes back next season, this secondary is going to need a nickname.