Examples:
The article talks about "police profilers." I didn't hear a single "profile" from any official agency. Everything was either "consultants," who explicitly said they had no clue as to what police were actually thinking or looking at, or "sources," who told us, anonymously, what police were thinking. Neither is any evidence as to POLICE incompetence.
As to the "Illegal aliens." They were not stopped just becasue they were Hispanic. The police were staking out a phone booth (they may have been incompetent not to get there a couple of minutes earlier -- I dunno) -- and the aliens were the people who showed up to use the phone.
As to the lying witness at the Home Depot -- the cops did figure that out pretty quick -- based on the in-store cameras that showed the witness inside when he said he was outside. As to the White Van/Truck -- that's what a number of witnesses said they "saw in the vicinity" (maybe they did -- the shooters just weren't in it!), and you can imagine the conspiracy minded if the police had "hushed up" their stories.
On balance -- I think the cops did OK -- not great, because the shooters would not have been caught so soon if they had not scattereed some clues, but when they had the clues, LE got an ID and connecting evidence pretty quick. B- to B+ grade.