Most of my ganks work like this. Shield up, pop ghost then attempt to get the ult off on one of the enemies in lane. Since his passive reduces his cooldowns by one second each hit on champs(.5 on minions) it allows him to almost always have it ready. The reason for the heavy levels on the shield early on (maxed at 9) is because it gives you movement you need to get in there quickly, and assure a drag. Although he lacks an instant gap closer (such as flash or a champion ability) some builds say Flash is a better bet, however utility wise and distance covered in the duration of a drag, I use ghost.

tldr; His speed should be the gap closer if you are playing him right.

Do you have a ganking strategy with Skarner or do you mostly focus on sustained jungling? It seems as though he has a very weak gank because he doesn't have a gap closer.