Typically in baseball if you are leading the division or have a strong chance for the wild card spot you'd be a buyer not a seller. So trading Dozier wouldn't make sense unless you were overstocked at the position and you thought Dozier would get you a pitcher you need.
In this circumstance you'd look at your prospects and what you'd need for your team, look at players who are in their final year (so they won't be your concern in the off season unless you really want him as an FA) and figure who you'd be willing to part with to get the missing pieces. The non-waiver trade deadline is July 31, so you could wait and see if the Twins form is holding then make the call on a trade.
Having said all that it is your game and your franchise so you can do what you wish. if you want to sell, looking at FA-to-be for future stars would be the way to go, usually trading such players in July. I don't know if they have a trade block anymore or if the CPU offers trades well but ideally that would be a way to gauge what teams are willing to give you for a player, or initiate a trade offer you think is fair.
But typically in early July to start selling when leading the division may result in your fan base checking out where to buy pitchforks and torches.