What happened to Tyreek this year?

Most of the first/second round busts have an explanation I understand (e.g. CMC's injury). But I didn't watch enough Dolphins games to get context on why Tyreek dropped to WR18 this year. At first I figured it was Tua's absence, but even after Tua game back Tyreek didn't light up the score sheet. I wanted to ask those who have done research/watched the games, because as I see it there are a few possible explanations:

• Was Tyreek injured? I know there were some questions about his wrist, did this translate into drops?
• Did the Miami offense overall suffer for some reason? I know Waddle wasn't doing to well either
• Did the Miami offense change to emphasize the short passing game? Jonnu and Acahne both ate
• Did defenses decide to sell out and stop Tyreek? If so, why is that different from any previous year?
• Has Tyreek finally just lost a step, and without his straightline speed, he's not a top tier receiver?