5.25 is plenty good for a OG, especially one who weighs around 320 pounds.
I think if you are interested in explosiveness then you are going to be more interested in broad jump and vertical jump.
40: 5.23
BJ: 8-8
VJ: 29
BP: 30
Arm length: 34.75
DeCastro
40: 5.32
BJ: 8-2
VJ: 29.5
BP: 34
Arm length: 32.38
Kevin Zeitler
40: 5.32
BJ: 8-5
VJ: 29
BP: 32
Arm length: 32.75
Peter Konz:
40: 5.16
BP: 18
Arm length: 33
Chance Warmack
40: 5.49
BJ: 9-2
Arm length: 34.68
Jon Cooper
40: 5.06
BJ: 9-0
VJ: 27
BP: 35
Arm Length: 33
So when compared to some of the other top interior OL prospects over the past couple of years Leary arguably had as good a combine as a power player as anyone when you combine his leg drive (VJ & BJ), speed (40), power (arm length x BP).
You could argue that one of the most important measurements for an OL is arm length and Leary has the longest arms but still has great power and explosiveness.
Anyhow, you can argue all you want about the relevance of the numbers but I would say it is hard to argue Leary didn't have one of the best Combine performances and has plenty of power and explosiveness to play in the NFL. The thing that I am more concerned about with OL is intelligence and ability to process the game quickly to pickup all the different games defenses like to play upfront. His lateral agility wasn't great at about 4.91 but his arm length and strength can probably make up for some of that.