First, what does your careers page look like? Sometimes the job description is unclear or you might be filtering out qualified people. Second, mid-senior is really tough to hire for, I just experienced it first-hand while hiring for my last employer. Regardless of experience level, you are forced to compete on two fronts: interesting work, or high compensation. Mid-senior devs can afford to be very picky and if something seems a little bit off, they'll look elsewhere.
Have you partnered yet with a recruiting company? I personally just went through TripleByte and they could use a few more NYC partners. They do their own pre-selection of candidates to save everyone involved a lot of time. Another good one is FunctionalWorks. Meetups are also pretty good for making organic connections with higher-quality devs. Every time I go to a tech meetup at least 3 or 4 employers are represented and hiring.
Have you partnered yet with a recruiting company? I personally just went through TripleByte and they could use a few more NYC partners. They do their own pre-selection of candidates to save everyone involved a lot of time. Another good one is FunctionalWorks. Meetups are also pretty good for making organic connections with higher-quality devs. Every time I go to a tech meetup at least 3 or 4 employers are represented and hiring.