I think you could do something close in Workfront. We need to break it down a little
If you're looking for just issues (not tasks) that are closed/resolved vs just issues that are any other status, you can put in two calculation columns. In the reporting, you need to use the three letter codes for status rather than the full words (Go to Setup, Project Preferences, Statuses then select the issues tab to see the list).
So a custom column of:
displayname=Number Closed/Resolved textmode=true valueexpression=IF({status}="RLV",1,IF({status}="CLS",1,0))
Will give '1' for closed or resolved issues and '0' otherwise
You'll want that to total up based on grouping (user) so you can add a couple of lines to tell it what to do for grouping summaries (aggregation):
aggregator.function=SUM aggregator.valueexpression=IF({status}="RLV",1,IF({status}="CLS",1,0)) displayname=Number Closed/Resolved textmode=true valueexpression=IF({status}="RLV",1,IF({status}="CLS",1,0))
You can see where this is going - add a second column switching the calculation around (0 if it's closed/resolved, 1 otherwise):
valueexpression=IF({status}="RLV",0,IF({status}="CLS",0,1))
Of course you'll want to time stamp the issues (otherwise after a year I'll have 1,000 closed/resolved issues against a small number of not closed).
Now to get that as an average, you can change the aggregator to an average rather than a sum:
aggregator.function=AVG aggregator.valueexpression=IF({status}="RLV",1,IF({status}="CLS",1,0)) displayname=Close % textmode=true valueexpression=IF({status}="RLV",1,IF({status}="CLS",1,0))
So those three columns will give you a count of closed/resolved, a count of not closed/resolved and a % calc (it will actually show 6% as 0.06 - you can multiply it by 100 or display it as a percentage).
So that's % closed issues. If you also want to look at tasks assigned to a person, you can create a separate report, and then combine the two reports on a dashboard.
Finally, looking at the ratio of tasks to issues you would need to do a report based on work items. I'm afraid I'll have to get back to that another time.