Hadst a lot do with implies that something or someone was heavily involved or influential in a situation or outcome. Some synonyms for this phrase include played a major role, greatly contributed, had a significant impact, was instrumental in, played a pivotal part, and was central to. Each of these phrases can be used to convey the idea that something or someone played a critical role in a particular situation. By using synonyms for hadst a lot do with, writers can add variety and nuance to their language and avoid repetition in their writing.