For its 4th attack, Aspect of the Agile Wolf fails to move the player in melee range before casting, as Shred usually does.
This means in combat situations with this aspect equipped, Shred is likely to regularely stop movement to cast the 4th attack locked in position, if the cursor is on a distant enemy. It basically works like a ranged cast, so it naturally breaks the flow of melee combat, as you miss your target and wont dash either (Primal Shred modifier), which can also be risky in its unpredictability.
You can test this easily in the training grounds. Go in range, then cast Shred on the target to see the character moving close before attacking. Repeat it four times and you will see that the 4th cast of Shred will not move.