This is what Oda told us in the last chapter and it totally make sense :
1. Garp confirmed that the CD escort ( Holy Knights) was more than enough to deal with rocks. He came to God Valley because Roger showed up.
2. Garling isn't the leader of the Holy Knights, there is no reason for him to be stronger than the others. And we know that WB got severly injured by Garling.
3. The Holy Knights are the ultimate protectors of the CD. They're obviously the strongest characters who works for the WG ( with admirals).
1. Garp confirmed that the CD escort ( Holy Knights) was more than enough to deal with rocks. He came to God Valley because Roger showed up.
2. Garling isn't the leader of the Holy Knights, there is no reason for him to be stronger than the others. And we know that WB got severly injured by Garling.
3. The Holy Knights are the ultimate protectors of the CD. They're obviously the strongest characters who works for the WG ( with admirals).