Keuchel is kind of the exception in that he was a pretty major addition. But he had a Cy Young on his mantle at home and was coming off a 3+ WAR season so I can understand making the exeption.
Cheerios wasn't a soft tosser. His fastball averaged 93.1 last year. He just struck batters out at the rate you would expect from a soft tosser.
AA will bring in soft tossers but they tend to be filler pieces. When he's targeting more significant acquisitions, he prioritizes velocity and Ks. Look at his pitcher signings this year. He re-signed Johnson (12.93 K/9, 96.1 MPH fastball), re-signed Jimenez (11.66 K/9, 95.4 MPH fastball), and signed Lopez (11.32 K/9, 98.4 MPH fastball).