Now mind you, as you can see Blades gives up catches too, but that's just football. No CB could ever keep from giving up receptions, but the difference is you see Blades is always within range & doesn't allow a ton of YAC, he plays through the hands & forces PBU's even after the ball is in the WR's hands, he also wraps his man up & stops the play immediately. You can't ask for much better than that, because when he has an opportunity to make a play on the ball he does, he flips his hips & gets his head around in time, that's based on proper technique & good eye discipline reading the WR & timing when to break on the ball.
With Ivey, what you see is a corner who doesn't read the WR at all, he doesn't have a clue when the ball is in the air & even when he does he's completely trailing his man, he opens his hips & is already beat off the line, he gives up leverage routinely. When he gives up catches, it's almost always for a big gain.
What he does well is play near the line of scrimmage vs the Run, he's basically a Striker playing Corner.