You wrote that if we were to bring in Fields, it would be fun to see them compete against each other, problem with that is, there are three possible elite WRs, any one.of them or all 3 could go within the top 10 picks...Miami needs an ALPHA receiver pretty bad, and will not get this chance again.
To get that receiver, Miami will need to use it's top 10 pick on the receiver they deem to be best for them, using the #3 pick on Fields (what it will take to get Fields), would still leave Miami without a receiver that can get behind the defense, can get WIDE open, and/or, will consistently catch the ball, and make plays when needed.
Not saying your idea to bring competition for Tua is bad, but using a 1st to bring competition against the QB you picked top 5 last year is not a good way to move forward with your Offense...Put weapons around your huge investment QB, If he continues to fail, you bring in someone else.
Heck, take a QB this year, just not early...If Fields happens to fall to the 2nd, take him.