Matzek was scratched from his start earlier this week at Triple-A Albuquerque, with the organization expressing a desire to have him work on his mechanics in a non-competitive environment, Nick Groke of the Denver Post reports. Matzek has had control problems dating back to when he first entered the organization in 2009, but after appearing to rectify things during his time in the majors last season, the issues resurfaced again this spring. After the lefty walked 19 batters over his first 22 innings with the Rockies, he was optioned back to Albuquerque, where he promptly allowed seven free passes in his first outing while lasting just one inning. Manager Walt Weiss believes Matzek is experiencing a mental block more than anything, and is hopeful that with a little time off, the 24-year-old can bounce back and contribute with the big club again later in 2015.