Plum, Mitchell and DeShields aren't the most efficient players, but they can knock down tough contested jumpers which makes them a unique asset. They are great bail out players if the offense isn't clicking and the shot clock is winding down. Some may question their shot selection at times, but if the game is on the line and it's down to the last few possessions, you put the ball in their hands for your best chance to win.
As an aside--these are the types of players that have led upsets of UCONN over the last several years. UCONN plays outstanding team basketball, but to beat UCONN, it's unlikely you'll do it through playing better team basketball. Notre Dame and Stanford have had their moments, but by and large, they haven't been able to come close when playing team basketball. When beating UCONN, usually there will be a player who UCONN can't contain and has been the difference maker down the stretch. If you look at UCONN's losses over the last 7 years, the bulk of them came against Notre Dame led by Diggins or McBride who both had several big games and made huge plays down the stretch in tight games. In 2012 when UCONN lost to Baylor, Sims took over (although Griner's 25 points, 9 rebounds and 9 blocks is worth a mention.) In 2015 UCONN couldn't stop Thompson or Orrange. No one would describe Diggins, McBride, Sims, Thompson, or Orrange as particularly efficient players, but they were all capable of stepping up their games and being great bail out players similar to Mitchell/Plum/DeShields. They have their hot and cold streaks, but when they are hot, they couldn't be stopped. These prototypes have found the most success against UCONN's stingy defense the last 7 years compared to any other player prototype....so that's why I give them a lot of credit.
