Why am I so bad?

Items in their inventory when the game ended, across 17 games.

Item	Games	Of all games	Win rate
Power Treads	12	70.6%	41.7%
Black King Bar	10	58.8%	40.0%
Magic Wand	6	35.3%	50.0%
Blink Dagger	6	35.3%	50.0%
Gem of True Sight	3	17.6%	100.0%
Arcane Boots	3	17.6%	66.7%
Aghanim's Scepter	3	17.6%	66.7%
Hydra's Breath	3	17.6%	66.7%
Butterfly	3	17.6%	33.3%
Mjollnir	3	17.6%	33.3%
Morbid Mask	3	17.6%	33.3%
Daedalus	3	17.6%	33.3%
Manta Style	3	17.6%	33.3%
Satanic	2	11.8%	100.0%
Harpoon	2	11.8%	100.0%
Consecrated Wraps	2	11.8%	50.0%
Eul's Scepter of Divinity	2	11.8%	50.0%
Monkey King Bar	2	11.8%	50.0%
Sange and Yasha	2	11.8%	50.0%
Wraith Band	2	11.8%	50.0%
Echo Sabre	2	11.8%	0.0%
Battle Fury	2	11.8%	0.0%
Spirit Vessel	1	5.9%	100.0%
Disperser	1	5.9%	100.0%
Khanda	1	5.9%	100.0%
Swift Blink	1	5.9%	100.0%
Force Staff	1	5.9%	100.0%
Tranquil Boots	1	5.9%	100.0%
Magic Stick	1	5.9%	100.0%
Wind Waker	1	5.9%	100.0%
Essence Distiller	1	5.9%	100.0%
Sentry Ward	1	5.9%	0.0%
Linken's Sphere	1	5.9%	0.0%
Cheese	1	5.9%	0.0%
Crystalys	1	5.9%	0.0%
Demon Edge	1	5.9%	0.0%
Wind Lace	1	5.9%	0.0%
Yasha	1	5.9%	0.0%
Null Talisman	1	5.9%	0.0%
Nullifier	1	5.9%	0.0%
Silver Edge	1	5.9%	0.0%
Claymore	1	5.9%	0.0%
Dust of Appearance	1	5.9%	0.0%