Mills, 26, was the Jays’ fourth round pick in 2007. He’s seen time in the big leagues in each of the last three seasons, pitching to a 8.57 ERA with 8.4 K/9 and 5.4 BB/9 in 48 1/3 innings spread across nine starts and five relief appearances. In 354 innings at the Triple-A level, he’s posted a much more respectable 4.32 ERA with 7.8 K/9 and 3.0 BB/9.
Mathis, 28, is a non-tender candidate, especially after the Halos acquired Chris Iannetta from the Rockies. He’s hit a miserable .193/.245/.282 in 771 plate appearances over the last three seasons while throwing out 24.7% of attempted basestealers.