I don't agree with Joyner's color-coding system for cornerbacks, but I thought I'd take a look at how he came up with Boldin's stats against so-called "red" cornerbacks.
I don't know what Joyner has for which passes to Boldin came against which cornerbacks, but I do have the play-by-play charting done by Football Outsiders. Obviously, Joyner and Football Outsiders might have different defenders noted on different pass attempts (and they might both be wrong), but it's the best I can do.
Anyway, here's what Football Outsiders has for Boldin when he was primarily covered by one of Joyner's "red cornerbacks" --
vs. Phillip Buchanon -- 0-for-0
vs. Ronde Barber -- 1-for-2, 8 yards (other pass "overthrown")
vs. Daven Holly -- 1-for-1, 9 yards
vs. Fernando Bryant -- 1-for-2, 13 yards (other pass "defensed")
vs. Fred Smoot -- 1-for-1, 3 yards (WR screen caught 3 yards behind line of scrimmage)
vs. Shawn Springs -- 2-for-2, 5 yards
vs. Carlos Rogers -- 1-for-1, 6 yards
TOTAL -- 7-for-9, 44 yards (one overthrown, one defensed)
YPA -- 4.88
Considering that Joyner says Boldin averaged 4.9 YPA against "red" cornerbacks, these probably are most or all of the same plays Joyner used.
In addition, there were two plays that Football Outsiders marked as "hole in zone" coverage, with one of Joyner's "red" cornerbacks the closest defender. Both of them came against Tampa Bay's Cover 2 -- an 8-yard catch with Phillip Buchanon nearby and a 24-yarder near Ronde Barber. Those are the types of plays Joyner used to mark as "indirect" coverage and include in his totals, but now he doesn't use them at all.