Batteries degrade over time. My last phone (Samsung Galaxy S Vibrant) would only charge to 93%. It would never charge higher than that. Near the end of my use of the phone the battery would only last about 5 - 7 hours. This is with disabling GPS, WiFi, Bluetooth.
Also, Something has to be the "highest" user of the battery. Since you disabled the stuff that is usually the big users of battery, something else is taking that spot.
I would say try replacing the battery, you can get a new battery for the G2 for about $22.
See WikiPedia info on Lithium-Ion Batteries:
- Charging forms deposits inside the electrolyte that inhibit ion transport. Over time, the cell's capacity diminishes. The increase in internal resistance reduces the cell's ability to deliver current. This problem is more pronounced in high-current applications. The decrease means that older batteries do not charge as much as new ones (charging time required decreases proportionally).
- High charge levels and elevated temperatures (whether from charging or ambient air) hasten capacity loss. Charging heat is caused by the carbon anode (typically replaced with lithium titanate which drastically reduces damage from charging, including expansion and other factors).
- A Standard (Cobalt) Li-ion cell that is full most of the time at 25 °C (77 °F) irreversibly loses approximately 20% capacity per year. Poor ventilation may increase temperatures, further shortening battery life. Loss rates vary by temperature: 6% loss at 0 °C (32 °F), 20% at 25 °C (77 °F), and 35% at 40 °C (104 °F). When stored at 40%–60% charge level, the capacity loss is reduced to 2%, 4%, and 15%, respectively. In contrast, the calendar life of LiFePO4 cells is not affected by being kept at a high state of charge
Emphasis mine. But note that it does "not charge as much". Android will still report that the battery is at 100% because it is. It is charged to the full capacity that the battery can handle. This is why it doesn't seem to hold a charge for as long as it used to.
Your battery is over 2 years old. Read this post from XDA about Li-Ion batteries that it quotes this site as the source.
Your lithium-ion battery starts dying the moment it leaves the factory
The fact is, your lithium-ion battery starts dying the moment it leaves the factory! Of course, the actual life-span of an unused lithium-ion battery can vary by a fair amount based on its internal charge as well as the external temperature. But suffice to say that you can expect to irreversibly lose 20% of a lithium-ion battery’s charge every year from its original date of manufacture.
Other things can even make these numbers worse. Like frequent discharges, keeping the battery in non-optimal temperatures and leaving the battery "sitting" idle for periods of time.