T-Mobile has climbed ahead of Sprint in overall performance in the new RootMetrics national network report.

In measuring during the first half of the year, RootMetrics found T-Mobile earned an overall score of 71.5 out of 100 and Sprint scored 69.6 out of 100 in the same category. In RootMetrics’ previous report, which covered the second half of 2013, Sprint scored 68.2 and T-Mobile scored 64.3.

The separation between Sprint and T-Mobile in categories like Reliability Index and Call Quality was small but T-Mobile markedly outperformed Sprint in the Speed Index.

The speed boost for T-Mobile is likely a result of the carrier deploying “wideband” LTE in 15x15 MHz and 20x20 MHz blocks. T-Mobile recently said it intends to deploy 20x20 in all major U.S. markets. That focus on metro areas is paying off for T-Mobile in the report, with the carrier winning or tying 169 times across all categories.

But RootMetrics said Sprint’s stay at the bottom of the Speed Index could be short-lived since the carrier is actively putting its 2.5 GHz spectrum to use for its tri-band Spark network, which Sprint sees hitting downlink speeds of around 50-60 Mbps.

Sprint and T-Mobile, despite positive progress, still well trailed Verizon and AT&T in overall performance. Verizon scored an 81.6 out of 100 and AT&T scored 79.5 out of 100. Verizon narrowly beat out AT&T in reliability but handily passed up Big Blue in the Speed Index. RootMetrics attributes Verizon’s high speed score at least in part to its XLTE AWS network deployment boosting speed and capacity.