If Darvish cannot be obtained, which is highly likely, then I do not believe that stooping to Cobb or Lynn is the correct approach. On the surface, it sounds logical, why not add quality starting pitching for a more reasonable price than the big fish on the market? Well here's why: Cobb and Lynn are undoubtedly going to be overpaid by somebody this year. It's inevitable. Despite Lynn's good ERA of 3.43, his FIP was an almost-disasterous 4.82! Clearly, Lynn was the beneficiary of a lot of good luck, as his .244 BABIP would suggest. That contract has the potential to be a disaster for whoever decides to fork up the money. As for Cobb, the 2.91 K/BB is a concern, though his strikeout numbers are fairly low at just over 6 K/9, he averages more than 2 BB/9. Not disastrous, but the lack of strikeouts is undesirable. His 4.16 FIP shows the possibility for regression, though the risk is far lower than Lynn. Cobb has been considered a "almost perfectly league-average pitcher," which is not an insult. However, because it is so much easier to find below average pitching than above, it is likely that his price tag will still be much too high in relation to the value he would actually add to the team. To that end, Fangraphs, if you look into their numbers, predict the performances of Kyle Gibson and Adalberto Mejia to be comparable to that of Lynn and Cobb. Yes, believe it or not, it is quite possible that the Twins could comparable production from those two unlikely sources for the cost of their contracts (Estimated value of $5.3M for Gibson after arbitration and league minimum $535K for Mejia) less than $6M, for similar production as opposed to, perhaps, upwards of $15M per year.
Jake Arrieta would be a more impactful investment, but I met Kevin Slowey a couple of months ago and he said that he doesn't think that Arrieta would consider the Twins, given that he is a Boras client. He said that Darvish is more likely.
Best bet, in my opinion:
Plan A: Try to land Darvish or Arrieta
Plan B: Try to find a taker for Miguel Sano (if anyone wants him amid the reports) and get a starting pitcher in return.
Plan C: Ride it out with the kids we have coming up. As I said, the value for Gibson and Mejia may not end up being significantly different than that of Cobb or Lynn, so save the money, and roll with Berrios, Santana, Gibson, Mejia, and whoever wins the #5 job (Hughes may be the frontrunner if healthy)