Shields require a lot of brainpower and a high skill ceiling if you're not up against incompetent, worthless potatoes.

Shieldbots reliance on their shield for both offense and defense means you have to pick your engagements extra carefully if you don't want your whole 10k of metal to go up in smoke in one unfortunate mistake.

You have to:
a) Maintain a constant ground screen to prevent Snitch sneaks
b) Field a large burst-fire AA in order to discourage Likho punishes
3) Be on a constant alert for a tactical missile sound and immediately change ball direction, just so you can dogde that imminent Shockley.

Shieldbots is a lot, A LOT of effort. These days I find tanks to be much more straightforward.