Many small-cap biotech stocks are super-risky, with no products on the market yet. Some big-cap biotech stocks, on the other hand, aren’t growing like they used to. Mid-cap biotech stocks could meet Goldilocks’ criteria of finding what is “just right.” Three mid-cap biotechs, in particular, look like winners. Here’s why it could pay off to buy shares of Clovis Oncology (NASDAQ: CLVS), Exelixis (NASDAQ: EXEL), and Seattle Genetics (NASDAQ: SGEN) in February.