I didn't say it wasn't an upgrade, but rather a replacement. Replacements can be upgrades.
And by the way, that 18 goal season was with a shooting percentage 40% higher than his career average, including that season. It's best not to count on significant statistical aberrations when projecting what a player is capable of.
The guy has scored 23, 18, 16, 12, 10, and 9 in his most recent complete seasons. Something in the range of 15 goals would not be out of line with his career production. Considering our third and fourth lines last year almost never scored, that's welcome production.