Weakness identification in technique is rather subjective since it depends on the eyes and judgement of a human being, namely the coach. The coach has his sets of belief and his preferences, which translate in a certain kind of technique he likes to see or push. Moreover, it is also subjective because every lifter is different in the way he lifts (timing, speed, explosiveness, etc.) and these differences can be made more apparent depending on body types.
For instance, a very short individual will always look faster than a taller lifter because the movement will require less time, less absolute body movement and less bar height (note : some exception exist). That is not an excuse to not be coached, but since live coaching is of the qualitative nature, the informed athlete should seek a coach he agrees with in terms of technique and the uninformed athlete should seek a coach that has athletes who ”seem” to be good lifters.
Inversely, if a lifter has a 100kg clean and a 150kg front squat, that means that he can front squat 150% of his clean. I have often seen lifters who have this kind of ratios between the clean and front squat. Interestingly enough, whenever they can’t stand up with the weight, more often than not they think that they need to work on squats further. These ratios, instead, suggest that the lifter is not efficient enough to use all of the strength he has in reserve. The problem in this case is not strength, but technical. With a 150kg front squat, we can easily expect a 130kg clean, if not 135-140kg. Thus the ratios tells us that we should be spending more time of refining the clean technique at that point in time since the lower result in the clean has to be due to technicalities and timing mistakes. Again, it does not mean to stop working on the squat, but to focus on the clean at this moment in time (read : not forever).
Ratios vary amongst individuals, weight classes and body types, so you should not be using ratios very strictly (to the T) and use them to have a general idea of where your priorities should be at this moment in time. You can only progress in this sport by working on things you are weak at, rather than things you are strong at. For instance, people with very short femur (thighs) tend to have incredible squats in comparison to their pull whereas taller athletes often have weaker squats in comparison to their pull.
Snatch to clean and jerk ration : 78-82%
Most elite lifters will snatch between 78 and 82 % of their best clean and jerk in competition. Again, there are some exceptions to this : Andrei Rybakov being the poster boy of this. In 2002, at the Junior Worlds, he snatched 182,5kg and clean and jerked 187,5kg as an 85kg. For the majority of lifters though, the snatch will be around 80% of their clean and jerk. Many beginners or crossfitters I have worked with will have ratios way below that (read 55-65%) which highlights that they should focus on the snatch.
Back squat to clean and jerk : 127-139% (+/- ~5%)
According to Ivanov (1976), Russian master of sports and MSIC had back squat to clean and jerk ratio of 122 to 144% depending on weight classes. 52kg lifters had a ratios of 139.6% +/- 7.5% which was similar to the 110kg lifters (139.2% +/- 5.5%). Middleweight lifters (75 and 82.5kg) however had a ratio of 127% +/- 5% which is probably due to biomechanical reasons. Indeed, there is often not much height difference between heavy (not super heavy) weight athletes and middle weight athletes and a huge difference in muscle mass. Anyhow, if you are squatting more than this, chances are that you should be focusing on the lifts more right now.
Many people have different ratios for the front squat. Many say that only 105% of your clean and jerk (105kg for a 100kg clean) is enough while others say 89% of the best back squat (117kg for a 100kg clean). Truth be told, anywhere in the middle is good. Personally, I like 110% of the clean for a double.
Power to full lifts : 85 to 9o %
It has been advocated to power 90% of the full lift PR. Personally, I have seen more weightlifters have ratios around 85% and many crossfitters have ratios around 105-110%. If you can power snatch more than you can snatch, you know where to put the work.
Push Press to clean and jerk : 75%
I put it there but I would say that I don’t look at this one so much. I think that the push press is not a determinant of performance for the jerk, but I use it to work dip mechanics and develop overhead stability
Muscle snatch with no leg contact to Snatch : roughly 60%
Not much to say here other than if you have trouble muscle snatching 60% of your best snatch without touching the legs, then you may need to work on extension work and strength off the ground.
I used pictures of Wonderlifter. Here is Wonderlifter’s facebook.