The phrase "to add another striker" means to bring in or recruit one more player, specifically someone who specializes in scoring goals for a sports team. Full definition
Simply if we don't add another striker, our title push will be over before it's even started. (justarsenal.com)
Yes, that's my take as well, we need to add another striker type so that we can change the tactics and style according with the team we play against. (justarsenal.com)
Can we afford to not add both a striker and a defender this month? (justarsenal.com)