Officially IBM saying about Arvind's accomplishments:
"Arvind Krishna is the Chairman and Chief Executive Officer of IBM. As a business leader and technologist, he has led the building and expansion of new markets for IBM in artificial intelligence, cloud, quantum computing, and blockchain."
https://newsroom.ibm.com/Arvind-Krishna#:~:text=Chairman%20and%20Chief%20Executive%20Officer,%2C%20quantum%20computing%2C%20and%20blockchain.
Let's see Arvind's scores card -
Blockchain - failed
Cloud - IBM cloud aka Softlayer - failed
Artificial intelligence - Vela? - are you kidding me...
Quantum computing - 10 years in the making and... Oh it's an experiment
What score should we give to AK including on his pre CEO accomplishments?
Layoffs and selling Watson and other things not cited by IBM's post.