SPACI score report for 3byn in ASTRAL 2.01:

PDB Entry: 3byn
SPACI score: 0.44
AEROSPACI score: 0.44

Experiment type: XRAY
Resolution: 2.1
R-factor: 0.181
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 1
PCK3 PROCHECK H-bonds: 2
WCK1 WHAT_CHECK Packing: -1.306
WCK2 WHAT_CHECK Ramachandran: -0.833
WCK3 WHAT_CHECK Chi angles: 0.845
WCK4 WHAT_CHECK Backbone: 1.127

Note: Here are links to pages about PROCHECK and WHAT_CHECK.

Here is the full WHAT_CHECK report on this protein (linked from the WHAT_CHECK site).