When you are throwing a route like he did. You throw it high, you throw it quick. It's all about timing, especially in the 1v1 matchup. I keep seeing people criticize the "decision making" but there's no decision making in a throw like that. It's not a pass you can wait a second or two on and still have any chance of completing it.
Kapernick didn't throw it well enough and Sherman made a great play. That's what led to the interception, not some vague, etherial notion of kaepernick regressing or whatever narrative you're trying to push
The fumble and the interception before that though were 100% on the QB and cost the 49ers the game just as much, and kaepernick owned up to that.