An old colleague of mine always used to say: 'You can't fire a canon from a canoe!'
How very true this is. A good wide base is the foundation for explosive movement and great stroke stroke production.
Look at Eugenie Bouchard (you may remember at Wimbledon 2014 she became the first Canadian-born player to reach the finals of a Grand Slam in singles, finishing runner-up to Petra Kvitova) hit a few balls here.
Pay particular attention to the width of her base as she executes her split step as her hitting partner is striking the ball. (Video courtesy of Everyballer Amelie Brooks who is currently out competing at the Moratoglou Academy and was able to watch Bouchard training).
Something we can all seek to emulate, whatever level we play at!