I don't agree with this.
Velasquez is somewhere between our 4th and 7th starter depending on what happens with Howard, Moore and Anderson.
If we assume for a moment hes the 4th starter then hes equivalent to Ian Anderson, Marcus Stroman and Jon Lester among our division rivals. If hes the 5th starter then its Bryce Wilson, Joey Lucchesi, and Joe Ross.
Hes not the best of that bunch, I'd definitely rather have Stroman or Anderson for example but I don't think he compares unfavourable to the group as the whole.
ZIPS projects all of that group but Lester (0.8) and Ross (0.7) for between 1.6 and 1.9 WAR in 2021. Prorating their 2020 seasons into a full 162 (and taking 2019 for Stroman and Lucchesi) Vince had the fourth highest at 1.9.
He had a pretty bad ERA in 2020, but his FIP and xFIP were 3rd best among that group.
I'm not against putting him in the pen if there is a real plan to turn him into a lights out reliever, but I think a lot of the desire to move him is because people are tired of seeing him be a mediocre starter who didn't live up to his early promise, forgetting that most teams need a mediocre starter or two to fill out their rotation. That and the fact that his pitch style is slow and can be a slog to watch.
Our rotation as a whole looks fine to me. The Mets clearly are the standout team in that perspective but I think we should get similar production from our starters to the Braves and Nationals, barring injury. Our everyday 8 was among the best in the league last year so if the pen can be mediocre rather than historically bad then the Phillies have a shot at a wild card. If the pen is good and there is a breakout from one or two players (Eflin, Kingery, Bohm, Howard, Hasely etc) then we can hope for a division title.