If getting Ryu entails an $80M+ investment then I would more than happy with Toronto turning their focus to Keuchel.
Keuchel has not been getting a lot of focus in Blue Jays land because the need is a top of the rotation starter and Dallas Keuchel ostensibly seems to be trending towards a mid-rotation option, or worse. He is almost 32, averaged about 88mph on the fastball last year, and he had a 4.72 FIP.
Based on the negatives MLBTR said in their Ryu article today that their initial prediction of a 3/$39M contract for Keuchel still seems reasonable. That's a stone's throw from tacking one extra year onto the Tanner Roark contract.
But I think there is some under the radar value with Keuchel. He has averaged 89.1mph in his career so his 88.4mph mean in 2019 was not far off his normal - he just was not able to reach back for the 90mph+ as often. The late start and abnormal spring might have had something to do with it.
Keuchel's K and BB numbers in 2019 were generally in line with his career marks. He still had an ERA under 4 and on his bWAR was a healthy 2.1 in his 112.2 IP. His DRA on BP was a decent 4.25, good for 1.9 WARP in his abbreviated season. So if he had have pitched a full season with his rate stats he would have approached or surpassed 3 wins by any measure other than fWAR.
He's a year younger than Ryu. He offers the promise and potential of stability that Ryu lacks. Yeah, there is less upside - Ryu is coming off a 5 WAR season and that upside is palpable for him and very likely not part of Keuchel's package anymore.
Remember that Toronto's main goal is rotation stabilization, it's not exactly to add a playoff Ace. Even if Keuchel is a #3/4 for the rest of his career, if he could reliably be that for the duration of his contract then he'd be a great signing, and in 2019 he could be the veteran leader the pitching staff needs. Toronto traded for Mark Beuhrle before his age 34 season and I think we can all agree Buehrle's 3 years with the organization were excellent.
If we think about a 3 or 4 year contract for Keuchel it's not hard to envision him being the grizzled veteran lefty that stabilizes the 2021 or 2022 rotation as this young core finally blossoms into a playoff team. The new Bark Meuhrle.