Being a former police officer for a large city in California, I've been in some tough decision making situations, and being a "Monday Morning Armchair Quarterback" is easy to point out the wrong, but I am going to do it anyway especially since I have experience!
When I first saw this footage on the news I could not believe the amount of shots that the ex-officer fired at the "suspect" with a knife, to me that was excessive. In a situation like this (person with a knife) I was trained to call for back-up, if the suspect advanced towards me then shoot to stop the threat, secure the suspect's weapon, handcuff, call for EMT and begin to administer first-aid. I was sickened while watching the footage from the second dashcam, the suspect was down, while I listened to the radio in the background EMT was not even requested yet, not even the dispatcher notified that EMT was summoned, 9 officers do a tactical (a weak one at that) approach while another is approaching from a wide angle on the right and another just bee-boppin behind them was one of the most ridiculous thing I've ever seen with law enforcement policy and procedure. Sure, I am all for being cautious, but c'mon, a weak tactical approach by officers on a suspect that had not been moving for minutes? Sure, a suspect with a weapon can advance on you in 15' causing injury before you can draw your firearm and fire to stop the threat, but he had cover behind the transformer box after he shot the "suspect".
Judgment, training and leadership is very much needed here along with a a better criteria for psychological testing. The city psychologist desperately needs to reevaluate his standards that he feels is best for the cities demographics for allowing candidates to become police officers. They want upstanding citizens that are squeekie clean, the only problem is, is that you get a 22 year old that still lives at home (due to the economy most likely) who has no life experience being thrown into real world situations that probably have them soiling themselves. Fear can be a good thing, if harnessed and used properly, but this ex-officer sure did not understand that at all, again probably due to very little life experience and poor training and poor judgment.
I do not know all the ins and outs of this, but what was the original call the ex-officer received or was he performing a pedestrian stop (his lights were on so I question his reason for being there)? From what I've heard on the news and read in the paper (for what they are worth), the gentleman that was shot was known in the community and was a 'regular' on the streets of Seattle. If this was a pedestrian stop, then why was this ex-officer not familiar with the people in the community? He obviously does not understand the value and importance of the concept of "community policing", but then again, so many agencies these days no longer teach that.
Here is a tid-bit of information too that I know of as far as training goes. I went to a training seminar on handling bank robberies put on by another agency, and we did some scenarios, and a lieutenant that was one of the trainers from the agency told me I was "doing it wrong, I need to keep my finger on the trigger when I have my firearm out".

Anyone that has any experience with firearms and guns, been in the military, been properly trained knows that you "keep your finger straight and off the trigger until you are ready to fire". Even after I told him that what he was telling me was against my departments P&P and was not the way I was even taught in the Marines, he still told me I was wrong. Yeah, I almost wrote a novel for my course and instructor evaluation! These were/are the numbskulls that are training the officers and deputy sheriffs in Central Valley California, at least it was was 17 years ago, hopefully they changed the training, but from the demeanor, attitude and persona of some LE personnel, they most likely have only gotten worse. Case in point, the SPD.
Now I'll get off my soap box!