Its not building up arm strength. Its the Jays specific plan going with the limited pitches. He has mentioned multiple times he is good to pitch deep even last season, but can/could only throw what the team let's him
Tiedemann looked more like himself today with the temperature finally hitting 60 F for him. 3.2 IP, 73 pitches. 3 H (2 HR), 3 BB, 2 HBP, 2 ER, 7 K. Lots of whiffs