Lombardozzi is a temporary player. When Werth returns, it's not a sure thing that we want Span playing over Morse, Harper, or Werth. Morse is making contact and earned the benefit of the doubt with his performance last year. Harper is the future. Jayson Werth was hitting well (OPS+ of 121) before his injury. Span just isn't a big enough difference maker to shove any of those guys to the bench.
If we decided to move LaRoche (which I would disgaree with), then yes bring on Span. At this point we don't have the prospects to trade for a guy who would possibly just be place-holding until Werth gets back in the lineup, which should be August.
Trade LaRoche, who is gone at the end of the season. Get something for him now.
Harper/Span/Werth is a great outfield. Morse gets back to first, where he belongs. We straight platoon Lomboardozzi and Espinosa at second. Offensive improvement, or, at worst, we stay league average but have tremendous upgrade defensively.