Fangraphs write up from June this year:
Blalock was selected as a safety pick in the 32nd round of the 2019 draft under the assumption that he was heading to school, but at the end of the day, Boston had enough bonus pool money left to sign him for $250,000. He had an inconsistent full-season debut in 2021 but also showed significant growth in terms of velocity, sitting 93-95 mph while touching 97, with the velo complemented by excellent shape, including big hopping action. He entered 2022 as a potential breakout guy, but Blalock had Tommy John in March and never threw a pitch. Recently back from his rehab, Blalock’s made just a few A-ball starts before list publication and things look to be intact, so that breakout may upon us.
Blalock is again sitting 93-95 and has been up to 97. It’s easily a plus-or-better pitch, and Blalock’s secondaries (which weren’t great in 2021) have leveled up in quality. This either happened between the end of 2021 and when he had TJ, or during his rehab. His 77-82 mph curveball has huge depth, and Blalock now also has a harder gyro slider. His slider feel isn’t dialed in yet. It’s usually tough for hurlers with extreme vertical slots like Blalock’s to have changeup feel, and he might be able to develop a screwball-style pitch, but because of his ability to spin the baseball, it’s more likely Blalock continues to refine his slider until that’s his third weapon.
The 2023 season is Blalock’s 40-man evaluation year and I think this is a guy potentially vulnerable to the Rule 5 if the Red Sox leave him unprotected. Yes, he’s currently at Low-A Salem, but Blalock will be 23 next year, he clearly crushed his rehab program, and he has two pitches that could get big league outs right now in his fastball and curveball. Especially as he’s still building innings coming off the TJ, he could absolutely be popped as a reliever. It might be better for the Red Sox to push Blalock and give him a real shot to earn a 40-man spot. He could be a Fall League candidate to push his innings total.