In hindsight Phillips probably shouldn't have been drafted in the 2nd round because of the time it has taken him to get where he is now. That's not his fault but it's what happens when you get enamored with physical gifts alone and gamble on "boom or bust", "questionable motor" red flags.
Sure Soliai took 4 years to get there but he was a 4th round pick who was only asked to play the run on two downs as a more conventional 4-3 nose tackle. More is expected of Phillips. He could still turn it around but they cannot afford to wait another season for him to get there. Signs are pointing up. His play at the end of the season and the required commitment he has acknowledged are good clues though.