There's just a slight error in the calculation of the benfeits realized after costs.
We have to calculate the actual costs which represent the costs of 5.5 teams (4.5 teams is the cost savings and not the costs).
Cost = 5.5*12*100k=6.6 M
Benefits = 14.1 - 6.6 = 7.5 M
It wasn't a question. Just an issue with precision.
Not a question but calculations leading to other results and conclusions.