Diaz is rated as the No. 5 prospect in the Seattle Mariners farm system according to Baseball America. Diaz was a third round selection in the 2012 MLB Draft.
The player just below Diaz on Baseball America's top-10 list is outfielder Austin Wilson, who will also start the season in Clinton after spending 2013 in Seattle's Class-A Short Season affiliate Everett.
Wilson, a 22-year old from Los Angeles, was selected in the second round in the 2013 draft. Wilson hit .241 for the AquaSox last season with 27 RBIs and 20 extra base hits.
Infielders Jack Reinheimer and Justin Seager also make the move-up from Everett to Clinton.
"Reinheimer has done such a good job in the organization since being drafted by the organization last year," Steinmann said. "He's a really nice player."
Seager is the younger brother to Kyle, the Mariners starting third baseman. Kyle already has a home run on the season in the majors while Justin is hoping to make the right type of splash in Clinton.
Each infielder turned in 30 RBIs last season in Everett. Reinheimer had the better batting average, however, at .269. Seager led the AquaSox with 13 doubles.
The youngest player on the LumberKings roster is 18-year-old outfielder Tyler O' Neill, who hails from Maple Ridge, British Columbia, Canada. O' Neill spent 2013 with the Peoria, Ariz. Fall League squad. He was a third round pick in 2013.
"He has a lot of power and a little bit of speed, and hopefully we can help him develop those as the year goes along," Steinmann said.
There are a quartet of players who played for the LumberKings last season making their return.
Pitchers Mark Bordonaro and Kansas City area native Blake Holovach return in 2014 as well as catcher Marcus Littlewood and infielder Zach Shank.
Littlewood knocked in 18 runs in 60 games last season while Shank made an eight-game stint here while hitting 6-for-21.
On the mound, Holovach went 1-2 in 30 apperances while Bordenaro came in for 20 games and went 3-4 with a 4.65 ERA.
Clinton LumberKings at Cedar Rapids Kernels Today, 6:35 p.m., 100.3 WCCI-FM Probable starters: Diaz vs. Slegers