The San Francisco 49ers went out and got Darrell Jackson as a free agent from the Seattle Seahawks and with much promise. Jackson is a great possession receiver with great run-after-the-catch speed. He's not going to get past you much but he can do damage and the Seahawks knew this.
The 49ers did not.
The 49ers tried to send Jackson deep and running deep patterns and fly patterns is not what Jackson does well.
Now he's gone.