You can figure it out. That one plug that is wet seems out of place so I would focus on that cylinder. It also seems more white than the others. The blue smoke that you showed a pic of should make the plugs foul a bit more. All the plugs dont look to bad really. If it is a leak from the rings your compression would be low as well since both the oil ring and compression rings wear at about the same rate. It could be a worn out cylinder but that really is rare I believe. You can do the leak down test to rule out the bottom of the engine. Then rebuild the top. You might as well rebuild the top anyway since its the cheaper and easier way to go first vs changing the bottom.
