A lot of red flags on Cashner. He had good ERA and H/9 last season, but his K-rate, only good since his great 2012 K-rate, just plummeted last season, all the way down to 4.64, a loss of 3 K/9 -- Yikes! He seemed lucky on BABIP. His ERAs in 2015 and 2016 were nothing to get excited about; 2017 seems a lucky outlier. He did average about 6 IP per start. Next year is his age 31 season. Probably worth a one-year gamble, but the Ks falling off the cliff make him very risky for multi-year. At almost 3.5K/9, he also isn't a control pitcher.
With Vargas, you're buying the age 35 and beyond seasons of a guy who missed most of 2015 and 2016, although he pitched a full 2017. His K and BB are a lot better than Cashner's and he is a lefty, so he looks like a better bet, but how many years of a guy his age with just one good post-injury year are you willing to buy? One, perhaps 2? I don't like his 2017 HR rate, but other than that no red flags in his 2017 stats. You do have to consider the HRs, with CBP being a bit of a HR park. I certainly don't want either of these guys on a 3-year deal.