NEW YORK — Acquiring a marquee starter such as Blake Snell or Jordan Montgomery isn’t the only way the Yankees can meaningfully improve their pitching staff this offseason. They could also employ a less traditional approach and build around their bullpen, adding a high-leverage arm or two in an attempt to shorten games and minimize the importance of their starters going deep into outings. Enter Josh Hader. Hader, a three-time NL Reliever of the Year, is fresh off another dominant season. The soon-to-be-former Padres closer’s strikeout rate of 36.8% ranked within the top 1% of MLB pitchers, as …