This was very much my experience going through an acquisition like that. I was working at a company that served big customers. We bought a smaller company, with one of the goals being to expand to serving smaller customers.
What actually happened was that our management very quickly started telling the people who came along with the acquisition that they were doing everything wrong. The salespeople were selling wrong, the marketing people were marketing wrong, the customer support people were supporting customers wrong. Everything that the company we acquired did differently was seen as a problem.
Within about a year, anyone they hadn't pressured to adopt our practices had left and been replaced with a transplant from the Mothership. Another year later, the customers we picked up in the acquisition were rapidly leaving for other vendors. They simply couldn't work with us in a way that worked for their business anymore. Last I heard, pretty much the only remaining vestiges of the company we acquired were trademarks, and we were back to only having very large customers.